Fly into almost any big U.S. city and, if you know where to look, the ground below tells you which decade built it. A dense cluster of towers in the middle. A gritty ring of old warehouses and cheap apartments wrapped around it. Then neighborhoods that get greener, newer, and pricier the farther out you go — until, way out by the highway loop, a second downtown appears out of nowhere: office parks, a mall, hotels, thirty miles from the "real" city center.
That last thing shouldn't exist if a city is just one center with rings around it. Yet there it is — an edge city, a downtown that grew in the middle of nowhere.
Geographers spent a century trying to draw the city's hidden blueprint. They gave us competing models — rings, wedges, scattered nodes — each capturing a piece of the truth and missing the rest. This lesson is about reading those blueprints, knowing who drew them and when, and knowing exactly where each one falls apart.
A city looks chaotic from the sidewalk, but from above it sorts itself into patterns: where the offices go, where the factories go, where the rich and the poor live. Urban geographers built land-use models — simplified diagrams of a city's internal structure — to explain that sorting. Treat every one of them as a lens, not a law: each was built from a particular city in a particular era, and each breaks down when you move it somewhere else.
Underneath all of them sits one engine: bid-rent theory. The bid-rent curve describes how the price a user will pay for land declines with distance from the central business district (CBD) — the commercial core with the highest land values, tallest buildings, and greatest accessibility. Retail and offices outbid everyone for the scarce, expensive center because they need maximum foot traffic and accessibility; housing and industry, which need more space per dollar, spread outward where land is cheaper. Bid-rent is why cities form zones at all — it's the price mechanism the models are trying to draw.
The concentric zone model was proposed by sociologist Ernest Burgess in 1925, based on Chicago. It says a city grows outward from the CBD in a series of rings, like ripples on a pond. From center to edge:
Burgess's big idea: as the city grows, each ring pushes outward into the next (a process he called invasion and succession). The model's limit: it assumes a single center and flat, uniform land — it can't explain factories strung along a river or a second downtown by the highway.
Real World: Burgess built this from 1920s Chicago — a rail-and-streetcar city where nearly everyone funneled into one downtown. The moment cars let people and businesses leapfrog outward, the neat rings started to blur.
Land economist Homer Hoyt revised Burgess in 1939 with the sector model. Hoyt argued the city grows not in rings but in wedges (sectors) radiating out from the CBD along transportation corridors — rail lines, major roads, rivers. Once a particular land use takes root near the center, it extends outward along the same corridor, so similar uses cluster in a wedge. High-rent housing, once established on an attractive side of town, keeps growing outward in that same direction; industry follows a rail or river corridor out from the core.
Hoyt's key correction to Burgess: transportation shapes the city, so land use is directional, not perfectly circular. Its limit: like Burgess, it still assumes a single dominant CBD.
Real World: Think of an affluent corridor that runs continuously from downtown out to the wealthy suburbs along one commuter-rail line, while heavy industry hugs a river valley on the opposite side. That directional pattern is pure Hoyt.
Geographers Chauncy Harris and Edward Ullman proposed the multiple nuclei model in 1945. Their insight: a large modern city does not have one center — it has several independent nodes (nuclei), each attracting particular land uses. A port, an airport, a university, an industrial park, and an outlying business district each become their own gravity well, with compatible uses clustering nearby and incompatible ones repelling each other (heavy industry and elite housing avoid one another).
This model best captures the sprawling, car-dependent city where activity is decentralized. Its strength is realism for large cities; its limit is that it's less a tidy geometry than a description — harder to "read" at a glance than rings or wedges.
Real World: A metro area with a downtown, a separate medical district, an "airport city" of hotels and logistics, and a tech corridor — no single center dominates. That's Harris & Ullman on the ground.
The Latin American city model, developed by Ernst Griffin and Larry Ford (1980, later revised), blends a colonial-era core with modern growth — and crucially, its social gradient runs the reverse of the U.S. pattern. At its heart is the CBD, from which a thriving commercial spine extends outward, flanked by an elite residential sector — the best housing runs along the spine near the center, not out at the suburban edge. Around this core sit rings that improve toward the center and worsen toward the periphery: an inner zone of maturity, then a zone of in-situ accretion, then a zone of peripheral squatter settlements (barrios/favelas) on the outskirts, often lacking services (disamenity zones).
The takeaway to burn in: in the classic U.S. models, wealth generally rises as you move outward; in the Latin American model, wealth is concentrated near the center and along the spine, and poverty pushes to the edge. The gradient is flipped.
Real World: Many rapidly urbanizing cities of the Global South show fast-growing informal settlements on their outer fringe while elite districts hug the historic core — the spatial signature the Griffin–Ford model captures.
The peripheral model (associated with Chauncy Harris, 1997; the closely related galactic city model is often credited to geographer Pierce Lewis) describes the modern American metropolis as an inner city surrounded by a ring road (beltway) studded with nodes — edge cities, suburban business and shopping districts, and industrial parks — scattered like planets around a sun. The old downtown is now just one node among many; jobs, retail, and offices have decentralized to the periphery. This is the model that finally explains the "downtown in the middle of nowhere" from the hook.
Hold all six loosely. Each is a tool for a different city, era, and question — and naming a model's limit is itself an AP-rewarded skill.
What each shows. All three try to diagram a U.S. city's internal land use, and all three share a CBD at the center. What differs is the geometry of everything else.
How to tell them apart fast. Ask two questions. Is there one center or many? Many centers → multiple nuclei. If one center, are the zones circular or directional? Circular rings → Burgess; corridors/wedges → Hoyt.
What the AP asks you to do. Rarely just "name the model." Usually it hands you a diagram or a described city and asks you to identify the model, describe its structure, compare two models, or explain a strength or limitation. Comparison and application — not recall — earn the points.
Common student mistakes. - Mixing up rings (Burgess) and wedges (Hoyt) — the single most common error. - Forgetting the dates and theorists; the exam pairs the model with a name. - Treating the models as literal maps of a real city rather than simplified idealizations. - Assuming every model puts the poor in the center — true for U.S. models, false for the Latin American model.
Scenario 1 — Match the city to the model. A described city has a single dominant downtown, with high-income neighborhoods forming a continuous strip running from just outside the CBD all the way out to the wealthy suburbs along one major commuter highway, while factories line a rail corridor on the opposite side of town. Pattern: one center, but land use runs in directional strips tied to transport routes. Model: the sector model (Hoyt, 1939) — wealth and industry extend outward in wedges along corridors, not in rings. Apply: because the affluent strip and the industrial strip both radiate from the center along their own routes, distance-based rings (Burgess) cannot describe this city. Scale it: at the neighborhood scale you see one wealthy corridor; step up to the metropolitan scale and those corridors are the wedges that give the whole city its shape.
Scenario 2 — Where the model breaks down. A geographer tries to apply Burgess's concentric zone model to a modern Sun Belt metro and fails: there's a downtown, but also three separate outlying business districts near the beltway, each with its own offices, malls, and hotels. Where it breaks: Burgess assumes one center and rings defined purely by distance from it. This car-based city is polycentric. Better tools: the multiple nuclei model (Harris & Ullman, 1945) or the peripheral/galactic model (Harris, 1997), both of which allow many nodes. Lesson: a model isn't "wrong" — it's built for a different city and era; identifying the mismatch is the analysis.
Scenario 3 — The reversed gradient (scale up: neighborhood → city). On the outer edge of a fast-growing city, a self-built informal settlement lacks paved roads and reliable water, while the city's wealthiest families live in gated blocks along a commercial boulevard running out from the historic center. Pattern: quality improves toward the center, worsens toward the periphery. Model: the Latin American city model (Griffin–Ford) — an elite spine near the CBD and peripheral squatter settlements / disamenity zones at the edge. Apply: this is the reverse of the U.S. pattern, where the poor cluster in the inner zone of transition and the wealthy commute from the suburbs. Scale it: the single peripheral neighborhood you're standing in is one tile of a citywide gradient that only makes sense at the metropolitan scale.
Rings vs. wedges vs. nodes. Burgess = concentric rings (distance from CBD); Hoyt = sectors/wedges (direction along transport corridors); Harris & Ullman = multiple nuclei (several separate centers). Keep straight: rings answer "how far?", wedges answer "which way?", nuclei answer "how many centers?" A ring is circular; a wedge is a pie slice; a nucleus is a dot.
The Latin American reversed gradient. In U.S. models the inner ring is poor and wealth rises toward the suburbs; in the Griffin–Ford model the best housing hugs the center and the spine while the poorest squatter settlements sit on the periphery. Keep straight: U.S. = rich move out; Latin American = rich stay in. If a stimulus shows slums on the outer edge, think Latin American, not Burgess.
Theorist/date mix-ups. The exam loves to swap names and years. Lock in: Burgess — 1925, Hoyt — 1939, Harris & Ullman — 1945. Keep straight: the order matches history — rings first (1925), then transport-shaped wedges (1939), then the decentralized multi-node city (1945), as cars reshaped urban America.
Model vs. reality. A land-use model is a simplified idealization, not a photograph of any real city. Keep straight: if asked for a limitation, "no real city looks exactly like this" plus a specific reason (assumes flat land, one center, no cars) earns credit; "the model is wrong" does not.
1. A. The concentric zone model is Ernest Burgess, 1925 (Chicago). B is the sector model; C is multiple nuclei; D is the Latin American model. Fix: concentric rings = Burgess 1925 (Chicago).
2. C. Bid-rent theory: accessibility peaks at the CBD, so land values are highest there and decline outward. A reverses the curve; B is a mid-zone, not the peak; D contradicts the whole theory. Fix: land values peak at the CBD and fall outward (bid-rent).
3. B. Hoyt's sector model arranges land use in wedges along transport corridors rather than Burgess's rings. A is false (both keep a CBD); C describes neither U.S. model's intent; D is chronologically backward (1939 after 1925). Fix: sector model = wedges along transport corridors (direction, not just distance).
4. C. Several independent centers = the multiple nuclei model (Harris & Ullman, 1945). A assumes one center; B is an agricultural model; D is about city sizes, not internal structure. Fix: many centers = multiple nuclei (Harris & Ullman 1945).
5. C. A CBD with a spine and elite sector, plus rings that worsen toward the periphery ending in squatter settlements, is the Latin American (Griffin–Ford) model. A and B are U.S. models with the opposite gradient; D is about edge cities on a beltway. Fix: spine + elite sector + peripheral squatter zones = Griffin–Ford.
6. A. The ring just outside the CBD is the zone of transition (industry + deteriorating housing). B is the outermost ring; C is farther out; D belongs to the Latin American model. Fix: ring just outside CBD (industry + decaying housing) = zone of transition.
7. B. Land value falling steadily with distance from the center is the bid-rent curve. A denies a single center (the data assume one); C is a social, not land-value, gradient; D concerns population ranks. Fix: land value declining with distance from CBD = bid-rent curve.
8. C. Directional wedges along a rail line and a river = Homer Hoyt (1939), the sector model. A would predict rings; B would predict several centers; D is the Latin American model. Fix: wedges along corridors = Hoyt 1939 (sector).
9. A. In Griffin–Ford, the wealthy cluster near the center/spine and the poor live on the periphery — the reverse of U.S. models. B is false (it has a CBD); C describes Burgess; D is false (informal settlements are central to the model). Fix: Latin American gradient is REVERSED — rich stay in, poor pushed out.
10. B. Edge cities on a suburban beltway are the signature of the peripheral/galactic model. A has only one center; C is an inner ring, not a suburban node; D addresses only the old downtown. Fix: edge cities on a beltway = peripheral/galactic model.
11. A. A continuous wealthy strip from center to edge is one wedge — the sector model links the neighborhood scale to the whole-city structure. B concerns city sizes; C is agricultural; D is about population change. Fix: a wealthy strip = one wedge (sector model at metro scale).
12. D. The concentric zone model assumes one center and uniform land, so it struggles with polycentric, car-based cities. A is false (it centers on the CBD); B is false (it is a diagram); C is false (it was based on Chicago). Fix: Burgess's limit = assumes one center + uniform land (fails for polycentric cities).
13. D. The multiple nuclei model is Harris & Ullman, 1945 — so naming Hoyt and 1925 is two errors (wrong theorist and wrong year). A, B, C undercount the mistakes. Fix: multiple nuclei = Harris & Ullman 1945 (not Hoyt, not 1925).
14. D. Poorest settlements on the periphery fit the Griffin–Ford reversed gradient. A is the opposite gradient (U.S. poor are central); B forces a single wedge that doesn't fit; C is false (the model does have a CBD). Fix: informal settlements on the fringe = Griffin–Ford periphery.
15. B. The models are simplified idealizations that fit some cities and eras and break down for others — tools, not universal truths. A overstates their accuracy; C is false (all include a CBD except where noted); D is false (different years). Fix: models are lenses, not laws — each fits some cities/eras, breaks for others.
FRQ 2 gives you one stimulus and asks you to analyze and apply. Read the described diagram carefully before writing, and match every answer to its action verb.
Stimulus — Urban land-use diagram (described): The diagram shows a single central business district (CBD) at the middle of the city. Radiating outward from the CBD in straight wedges are bands of land use: one wedge of high-income residential housing extends continuously from near the center out to the city's edge along a major highway; a separate wedge of industry runs outward along a rail line on the opposite side; and additional wedges of low- and middle-income housing fill the remaining directions. The bands are pie-slice shaped, each anchored at the CBD and widening as it reaches the periphery. There is only one center, and land uses are organized by direction (which corridor) as much as by distance.
Question (7 points):
(A) The sector model. (One or two words is enough for "identify.")
(B) Homer Hoyt, 1939.
(C) The city has a single central business district at its center, and land uses radiate outward from it in wedges (sectors): a high-income residential wedge runs along a highway to the edge, an industrial wedge follows a rail line on the opposite side, and other wedges hold low- and middle-income housing. Each pie-slice band is anchored at the CBD and widens toward the periphery. (Observable structure only — correct for "describe.")
(D) Transportation corridors such as highways, rail lines, and rivers create routes of high accessibility, so once a land use establishes itself near the center along a corridor, it extends outward along that same corridor; similar uses therefore cluster into a directional wedge rather than a ring, because businesses and residents locate along the route that best serves them. (A because/mechanism — correct for "explain.")
(E) Similarity: both the sector model and the concentric zone model place a single CBD at the center of the city. Difference: the concentric zone model (Burgess) organizes land use into circular rings defined by distance from the CBD, whereas the sector model (Hoyt) organizes it into wedges defined by direction along transport corridors. (Explicit similarity AND difference — required for "compare.")
(F) (Any one, fully explained.) A strength is that the model incorporates transportation, so it explains why real land uses often run in directional strips — such as an affluent corridor following a commuter-rail line — that a purely ring-based model cannot capture, making it more realistic for many industrial-era cities.
(G) (Any one, fully explained.) A limitation is that the model still assumes a single dominant CBD and uniform terrain, so it cannot explain polycentric, car-based cities that grow multiple outlying centers (edge cities) — patterns better described by the multiple nuclei or peripheral models. (Naming a real reason it breaks down earns the point; "it's just wrong" does not.)
| Part | Point earned for… | Common point-loss |
|---|---|---|
| A | Naming the sector model | Saying "concentric zone" (rings) or "multiple nuclei" |
| B | Hoyt and 1939 both correct | Right model, wrong theorist/date; swapping in Burgess or Harris & Ullman |
| C | Describing the observable wedge/sector structure radiating from one CBD | Explaining why instead of describing; vague "it has zones" |
| D | Explaining that corridors channel like uses outward into wedges (a mechanism) | Merely restating that wedges exist without linking to transport |
| E | Stating one similarity (shared CBD) and one difference (rings vs. wedges) | Giving only a difference, or only a similarity — "compare" needs both |
| F | Explaining a genuine strength with a reason (captures transport-driven directional land use) | Listing a feature without saying why it's a strength |
| G | Explaining a genuine limitation with a reason (single CBD; misses polycentric cities) | "The model is wrong" with no specific reason |
Action-verb callout: Parts A and B say identify — a name, a date, a term; don't pad them. Part C says describe — state what the diagram shows, no causes. Parts D, F, and G say explain — each needs a because/mechanism. Part E says compare — you must give both a similarity and a difference; writing only one caps you at partial credit.
Comparison callout: On "compare," graders literally look for two things — the similarity and the difference — stated explicitly. Signal them: "Both models…" and "However, they differ because…"
1. A. The concentric zone model is Ernest Burgess, 1925 (Chicago). B is the sector model; C is multiple nuclei; D is the Latin American model. Fix: concentric rings = Burgess 1925 (Chicago).
2. C. Bid-rent theory: accessibility peaks at the CBD, so land values are highest there and decline outward. A reverses the curve; B is a mid-zone, not the peak; D contradicts the whole theory. Fix: land values peak at the CBD and fall outward (bid-rent).
3. B. Hoyt's sector model arranges land use in wedges along transport corridors rather than Burgess's rings. A is false (both keep a CBD); C describes neither U.S. model's intent; D is chronologically backward (1939 after 1925). Fix: sector model = wedges along transport corridors (direction, not just distance).
4. C. Several independent centers = the multiple nuclei model (Harris & Ullman, 1945). A assumes one center; B is an agricultural model; D is about city sizes, not internal structure. Fix: many centers = multiple nuclei (Harris & Ullman 1945).
5. C. A CBD with a spine and elite sector, plus rings that worsen toward the periphery ending in squatter settlements, is the Latin American (Griffin–Ford) model. A and B are U.S. models with the opposite gradient; D is about edge cities on a beltway. Fix: spine + elite sector + peripheral squatter zones = Griffin–Ford.
6. A. The ring just outside the CBD is the zone of transition (industry + deteriorating housing). B is the outermost ring; C is farther out; D belongs to the Latin American model. Fix: ring just outside CBD (industry + decaying housing) = zone of transition.
7. B. Land value falling steadily with distance from the center is the bid-rent curve. A denies a single center (the data assume one); C is a social, not land-value, gradient; D concerns population ranks. Fix: land value declining with distance from CBD = bid-rent curve.
8. C. Directional wedges along a rail line and a river = Homer Hoyt (1939), the sector model. A would predict rings; B would predict several centers; D is the Latin American model. Fix: wedges along corridors = Hoyt 1939 (sector).
9. A. In Griffin–Ford, the wealthy cluster near the center/spine and the poor live on the periphery — the reverse of U.S. models. B is false (it has a CBD); C describes Burgess; D is false (informal settlements are central to the model). Fix: Latin American gradient is REVERSED — rich stay in, poor pushed out.
10. B. Edge cities on a suburban beltway are the signature of the peripheral/galactic model. A has only one center; C is an inner ring, not a suburban node; D addresses only the old downtown. Fix: edge cities on a beltway = peripheral/galactic model.
11. A. A continuous wealthy strip from center to edge is one wedge — the sector model links the neighborhood scale to the whole-city structure. B concerns city sizes; C is agricultural; D is about population change. Fix: a wealthy strip = one wedge (sector model at metro scale).
12. D. The concentric zone model assumes one center and uniform land, so it struggles with polycentric, car-based cities. A is false (it centers on the CBD); B is false (it is a diagram); C is false (it was based on Chicago). Fix: Burgess's limit = assumes one center + uniform land (fails for polycentric cities).
13. D. The multiple nuclei model is Harris & Ullman, 1945 — so naming Hoyt and 1925 is two errors (wrong theorist and wrong year). A, B, C undercount the mistakes. Fix: multiple nuclei = Harris & Ullman 1945 (not Hoyt, not 1925).
14. D. Poorest settlements on the periphery fit the Griffin–Ford reversed gradient. A is the opposite gradient (U.S. poor are central); B forces a single wedge that doesn't fit; C is false (the model does have a CBD). Fix: informal settlements on the fringe = Griffin–Ford periphery.
15. B. The models are simplified idealizations that fit some cities and eras and break down for others — tools, not universal truths. A overstates their accuracy; C is false (all include a CBD except where noted); D is false (different years). Fix: models are lenses, not laws — each fits some cities/eras, breaks for others.
| Part | Point for | Verb |
|---|---|---|
| A | Sector model identified | identify |
| B | Hoyt and 1939 | identify |
| C | Wedge structure radiating from one CBD, described | describe |
| D | Corridors channel like uses outward into wedges (mechanism) | explain |
| E | One similarity (shared CBD) and one difference (rings vs. wedges) | compare |
| F | A real strength with a reason (captures transport-driven land use) | explain |
| G | A real limitation with a reason (single CBD; misses polycentric cities) | explain |
Top point-losses: (1) on E, giving only a difference or only a similarity — "compare" demands both; (2) describing on D/F/G instead of explaining (no because); (3) getting the model right in A but the theorist or date wrong in B; (4) writing "the model is wrong" for G instead of naming a specific reason it breaks down.
HumanGeoIQ · Lesson 22 of 30 · Unit 6: Cities and Urban Land-Use Patterns and Processes (12–17%)
This lesson is exam-preparation material for the AP Human Geography exam. AP is a trademark of the College Board, which does not endorse this product. Urban land-use models are attributed to their named theorists and dates and described qualitatively; no specific land-value figures, rents, or population counts are asserted, in keeping with the course's qualitative approach. Content pending external geography review.