Lesson 08: Congress — Behavior & Representation

Starter

Look at a map of Maryland's 3rd Congressional District or North Carolina's old 12th and you'll see shapes that look less like a community and more like a paint spill. One federal judge described a district as resembling "a broken-winged pterodactyl." These shapes aren't accidents. They are the product of a quiet, once-a-decade process where politicians get to draw the lines of the elections they will run in.

Here's the puzzle at the heart of today's lesson. The Constitution says the House represents the people. But who draws the districts that decide which people vote together? In most states, the answer is the state legislature — meaning the people in power get to design the next election. That's a little like letting players referee their own game.

When does line-drawing cross from ordinary politics into something a court will strike down? When is a member of Congress supposed to vote her own judgment versus do exactly what her district wants? Those two questions — how districts are drawn and how representatives behave — are the operating system of the House. Let's open it up.

Core Concepts

The House of Representatives is built on a single idea: representation by population. The Constitution (Article I, Section 2) requires an enumeration — a count of every person in the country — "within every subsequent Term of ten Years." That count is the census, conducted by the Census Bureau every year ending in zero (1990, 2000, 2010, 2020). The census does two jobs at once, and AP students mix them up constantly, so separate them now.

Apportionment vs. redistricting

Apportionment is the distribution of the 435 House seats among the fifty states, based on each state's share of the national population. After every census, fast-growing states gain seats and slow-growing states lose them. After the 2020 census, for example, Texas gained two seats while states like New York and California each lost one. Apportionment is a national, between-states process, and the number 435 has been fixed by law since 1929.

Redistricting is what happens inside each state afterward: states must redraw the boundaries of their congressional districts so that each district holds roughly the same number of people. In most states, the state legislature draws these lines (subject to the governor's veto). A growing minority of states have handed the job to independent or bipartisan redistricting commissions to take politicians out of the process. The key distinction: apportionment divides seats between states; redistricting draws lines within a state.

Because district lines are redrawn by whoever holds power, redistricting is where the temptation to cheat the map lives. That cheating has a name.

Gerrymandering: packing and cracking

Gerrymandering is the drawing of district boundaries to give one group an unfair advantage. The word dates to 1812, when Massachusetts Governor Elbridge Gerry signed off on a district so contorted it looked like a salamander — a "Gerry-mander." Two centuries later the technique is a science, and it works through two complementary moves:

• Packing crams as many of the opposing party's (or group's) voters as possible into a few districts. Those districts are won in landslides — 80%, 90% — but every vote piled up beyond 50%-plus-one is "wasted," so the opposition wins fewer seats overall.
• Cracking does the opposite: it splits a concentrated bloc of opposing voters across many districts, so they never make up a majority in any of them and elect no one.

A skilled mapmaker uses both at once — packing the opposition where it's already dominant and cracking it everywhere else — to win a majority of seats with a minority of votes.

Gerrymandering comes in two legally distinct flavors, and the difference decides whether a court will step in:

• Partisan gerrymandering draws lines to benefit a political party. In Rucho v. Common Cause (2019), the Supreme Court ruled that partisan gerrymandering claims are non-justiciable political questions — federal courts will not referee them. Remedies must come from state courts, state constitutions, independent commissions, or Congress.
• Racial gerrymandering draws lines using race as the predominant factor. This is treated far more strictly. Under Shaw v. Reno (1993), a district drawn predominantly on the basis of race triggers strict scrutiny under the Equal Protection Clause — the hardest test in constitutional law for a government to survive.

That difference — courts stay out of partisan maps but scrutinize racial ones — is one of the most testable ideas in Unit 2.

How courts got into redistricting at all

For most of American history, federal courts refused to touch districting, calling it a "political question" for legislatures. That changed with Baker v. Carr (1962). Tennessee had not redrawn its state legislative districts since 1901, even as people moved from farms to cities. The result: a rural district with a few thousand voters had the same one representative as an urban district with hundreds of thousands. The Supreme Court held that such malapportionment claims are justiciable — courts can hear them under the Equal Protection Clause. Baker opened the door to the principle that each person's vote should count equally, captured in the slogan "one person, one vote." Once districts had to be roughly equal in population, the map-drawing fight was on — and the courts were now in the room.

Models of representation

Suppose your district overwhelmingly wants a bill you personally believe is a mistake. How should you vote? Political scientists describe three answers:

• Trustee model: the representative uses her own judgment and conscience, voting for what she thinks is best for the country even if constituents disagree. (Edmund Burke's classic view: "Your representative owes you... his judgment.")
• Delegate model: the representative mirrors the expressed wishes of constituents, voting the way the district wants regardless of personal opinion.
• Politico model: the realistic blend — the representative acts as a trustee on some issues (especially complex or low-visibility ones) and as a delegate on others (especially high-visibility issues the district cares about intensely).

Real members shift among these constantly, weighing constituency, party, and conscience vote by vote.

The incumbency advantage

The single most powerful fact about House elections is that the people already in office almost always win. The incumbency advantage is the built-in edge an officeholder has over challengers, and it rests on four pillars:

• Name recognition — voters already know the incumbent's name, and recognition alone moves votes.
• The franking privilege — the right to send official mail to constituents at taxpayer expense, keeping the member visible between elections.
• Fundraising — incumbents attract far more money from donors and interest groups, who prefer backing likely winners.
• Casework — staff help constituents solve problems with the federal bureaucracy (a lost Social Security check, a delayed visa), building personal loyalty across party lines.

In Practice. House incumbents seeking re-election typically win at rates around 90% or higher, even in years when voters tell pollsters they "disapprove of Congress." That paradox — Americans hate Congress but re-elect their own member — is incumbency at work. Safe districts (often gerrymandered) make general elections noncompetitive, so the real contest shifts to party primaries, where more ideologically committed voters dominate. That dynamic helps explain rising polarization.

How Congress behaves: deals, money, and gridlock

Once in office, members trade. Logrolling is the mutual exchange of votes: "Support my bill and I'll support yours." Pork-barrel spending is the use of federal funds for localized projects (a bridge, a research center, a military contract) designed to benefit a member's own district and boost re-election; the line items that direct money to specific projects are earmarks. Both reward members for delivering tangible goods to constituents.

But cooperation is harder than it used to be. Partisanship — loyalty to party — has intensified into polarization, the widening ideological gap between the parties with fewer moderates in the middle. Combine that with divided government (one party controlling the presidency while the other controls one or both chambers of Congress) and you get gridlock: the inability to pass legislation because the sides cannot or will not compromise. The same checks that the Founders designed to prevent tyranny can, in a polarized era, also produce stalemate.

Document Spotlight: Baker v. Carr (1962)

Context. By the mid-20th century, Tennessee's legislative map was a fossil. The state constitution required redistricting after every census, but the legislature had simply refused to redraw lines since 1901. As population shifted to the cities, rural districts kept the same representation while urban districts ballooned — so a city vote was worth a fraction of a rural vote. Charles Baker, a voter in fast-growing Memphis, sued, claiming this dilution denied him "equal protection of the laws."

The constitutional question. Do federal courts have the authority to hear a challenge to the apportionment of legislative districts, or is malapportionment a non-justiciable "political question" reserved to the legislative branch?

The holding. The Court held that challenges to legislative apportionment are justiciable under the Equal Protection Clause of the Fourteenth Amendment — federal courts can hear them and decide them on the merits.

What it means. Baker did not itself redraw a single district. Its power was procedural: it unlocked the courthouse door. By rejecting the "political question" dodge, it allowed a wave of follow-on cases that established "one person, one vote" — districts must be roughly equal in population so each citizen's vote carries equal weight.

How it's used on the AP exam. Baker v. Carr is one of the fifteen required cases, and the exam tests it as the case that made redistricting justiciable and launched "one person, one vote." Cite it whenever a prompt involves courts reviewing district lines, vote dilution, or whether judges can intervene in apportionment. Pair it carefully with Shaw v. Reno: Baker is about jurisdiction and equality of population; Shaw is about race as a drawing factor. Confusing the two is one of the most common — and costly — errors on the exam.

SCOTUS Case Breakdown

Case 1 — Baker v. Carr (1962)

Facts of the case. Tennessee had not reapportioned its state legislative districts since 1901, despite a state constitutional command to redraw them after each census. Decades of population movement to the cities left urban districts with far more residents per representative than rural ones. Charles Baker, a voter in Shelby County (Memphis), sued Secretary of State Joe Carr, arguing the outdated map diluted his vote and denied him equal protection of the laws.

Constitutional question. Is the constitutionality of a state's legislative apportionment a justiciable question that federal courts may decide under the Equal Protection Clause, or is it a non-justiciable "political question"?

Holding. Apportionment challenges are justiciable under the Fourteenth Amendment's Equal Protection Clause; federal courts have jurisdiction to hear them.

Reasoning. Writing for a 6–2 Court, Justice William Brennan reformulated the "political question" doctrine, listing factors (such as a textual commitment of the issue to another branch) that make a question non-justiciable — and finding that apportionment met none of them. Vote dilution, the Court reasoned, is an ordinary equal-protection claim that courts are fully competent to judge using "judicially discoverable and manageable standards." The Court did not decide whether Tennessee's specific map was unconstitutional; it sent the case back for trial, having established only that the courthouse was open.

Impact. Baker set off a redistricting revolution. Within two years, decisions like Reynolds v. Sims (1964) applied the principle that legislative districts must be substantially equal in population — the doctrine of "one person, one vote." It is the foundational case for judicial involvement in districting and the natural counterpart to Shaw v. Reno: Baker establishes that courts may review district lines; Shaw establishes when a particular line-drawing motive (race) triggers heightened review.

Case 2 — Shaw v. Reno (1993)

Facts of the case. After the 1990 census, North Carolina gained a seat and, prompted by the Department of Justice under the Voting Rights Act, drew a second majority-Black district — the 12th. The district was extraordinarily irregular: a roughly 160-mile snake that for stretches was no wider than the Interstate 85 corridor it followed, connecting far-apart Black communities. Five white voters, led by Ruth Shaw, sued Attorney General Janet Reno, claiming the district was a racial gerrymander that violated their right to equal protection.

Constitutional question. Does a congressional redistricting plan that is so irregular in shape that it can be understood only as an effort to separate voters by race state a valid claim under the Equal Protection Clause of the Fourteenth Amendment?

Holding. Yes — a district so bizarre on its face that it is "unexplainable on grounds other than race" must be analyzed under strict scrutiny and is unconstitutional unless narrowly tailored to a compelling government interest.

Reasoning. Writing for a 5–4 majority, Justice Sandra Day O'Connor held that classifying and separating voters by race — even to help a minority group gain representation — is a racial classification that demands the Equal Protection Clause's most searching review. Such districts, she warned, resemble "political apartheid," reinforcing the stereotype that members of a racial group think alike and vote alike. The Court did not strike the district down outright; it remanded the case so the lower court could apply strict scrutiny and ask whether the map was narrowly tailored to a compelling interest.

Impact. Shaw established that race cannot be the predominant factor in drawing district lines without surviving strict scrutiny, sharply limiting the creation of majority-minority districts justified mainly by race. It is the racial-gerrymandering counterpart to the partisan-gerrymandering rule of Rucho v. Common Cause (2019): courts will not police partisan maps, but they will apply strict scrutiny to racial ones. On the exam, Shaw pairs with Baker (both are Equal Protection redistricting cases) — but keep their jobs distinct: Baker = justiciability and population equality; Shaw = race and strict scrutiny.

Application Practice

Work each scenario the AP way: identify the issue → state the relevant principle/case → apply it → predict the outcome.

Scenario 1 — The clever map. A state legislature, controlled by Party A, redraws the congressional map after the census. It concentrates Party B's voters into two overwhelmingly Party-B districts and spreads the rest thinly across the remaining ten, so Party A wins eight of twelve seats despite winning only 52% of the statewide vote. Party B sues in federal court, calling it an unconstitutional partisan gerrymander. Analysis: The techniques are packing (the two lopsided Party-B districts) and cracking (the thin spread elsewhere). The claim is partisan gerrymandering. Under Rucho v. Common Cause (2019), partisan gerrymandering is a non-justiciable political question in federal court. Predicted outcome: The federal suit is dismissed. Party B's realistic remedies are state courts, an independent commission, or a ballot initiative — not the federal bench.

Scenario 2 — Trustee or delegate? A representative's district strongly favors a popular tax cut that she believes will harm the country's long-term finances. She votes against it, telling constituents she answered to her own judgment. Analysis: This is a representation-model question. By substituting her judgment for the district's expressed preference, she is acting as a trustee rather than a delegate. Predicted outcome: A defensible choice constitutionally, but a politically risky one — on a high-visibility issue the district cares about intensely, trustee voting can cost an incumbent at the next primary.

Scenario 3 — The vanishing challenger. A first-time challenger struggles to raise money, can't match the incumbent's name recognition, and watches the incumbent mail district-wide newsletters at no personal cost while staff trumpet a constituent's resolved Social Security case. Analysis: Every advantage named is a pillar of the incumbency advantage — fundraising, name recognition, the franking privilege, and casework. Predicted outcome: Absent a scandal or a wave election, the incumbent is very likely to win; this is why House re-election rates sit so high.

Traps & Confusions

Baker v. Carr vs. Shaw v. Reno. Both are Fourteenth Amendment Equal Protection redistricting cases — which is exactly why they're confused. Keep their jobs separate. Baker v. Carr (1962) is about justiciability: it made apportionment a question courts can hear, launching "one person, one vote." Shaw v. Reno (1993) is about race: a district drawn predominantly by race triggers strict scrutiny. Baker opens the courthouse; Shaw sets the standard for racial maps.

Partisan vs. racial gerrymandering. This distinction controls the outcome. Partisan gerrymandering (drawing for a party) is a non-justiciable political question in federal court after Rucho (2019). Racial gerrymandering (race as the predominant factor) gets strict scrutiny after Shaw. Same word, opposite judicial treatment.

Trustee vs. delegate vs. politico. Trustee = votes own judgment. Delegate = votes the district's wishes. Politico = blends both depending on the issue. Memory hook: a trustee you trust to decide; a delegate is delegated instructions to follow.

Packing vs. cracking. Packing = stuff opponents into few districts so their extra votes are wasted. Cracking = scatter opponents across many districts so they're a majority in none. Both waste the opposition's votes — packing by surplus, cracking by dispersion.

Apportionment vs. redistricting. Apportionment distributes the 435 seats between states; redistricting draws lines within a state.

Practice Problems

FRQ Practice — Quantitative Analysis (FRQ 2)

The data. The table below shows approximate re-election rates for incumbent members of Congress who sought another term in selected election years. (Figures are rounded and illustrative of long-run patterns.)

Prompt. Using the data in the table, respond to the following.

(A) Identify the chamber that, across the years shown, had the more consistently high re-election rate.

(B) Describe a difference between House and Senate re-election rates shown in the data, and draw a conclusion about which chamber's incumbents face more competitive elections.

(C) Explain how the concept of the incumbency advantage helps account for the pattern of high re-election rates shown in the data.

Model Response

(A) — 1 point. The House of Representatives had the more consistently high re-election rate. Every House figure shown is in the mid-80s or higher (ranging from 85% to 98%), whereas the Senate figures swing more widely, dropping as low as 79% in 2000 and 84% in 2010 and 2020.

(B) — 1 point. The data show that Senate re-election rates are more variable than House rates: the Senate ranges from 79% (2000) to 100% (2022), a spread of 21 points, while the House stays within a tighter band (85% to 98%, a spread of 13 points) and never falls as low as the Senate's worst years. A reasonable conclusion is that Senate incumbents face more competitive elections — Senate races are statewide, more expensive, more visible, and harder to make "safe" through districting, so sitting senators lose more often than House members.

(C) — 1 point. The incumbency advantage is the built-in edge officeholders hold over challengers, and it explains why re-election rates stay so high. Incumbents enjoy name recognition, the franking privilege (free official mail keeping them visible), superior fundraising from donors who back likely winners, and casework that builds personal loyalty among constituents. In the House, this edge is amplified because many districts are drawn to be "safe" (noncompetitive) through redistricting, so incumbents rarely face strong general-election challengers — producing the consistently high re-election rates in the table.

Total: 3 points.

Common point-loss: - Part A: Naming the Senate, or failing to actually identify a chamber (the question requires picking one). A correct identification needs no explanation, but it must be the House. - Part B: Describing the data without drawing a conclusion about competitiveness — or, conversely, drawing a conclusion with no data reference. AP quantitative questions require students to use the numbers (cite specific figures or the range) and then interpret them. Reversing the relationship (claiming the House is more competitive) earns no credit because it contradicts the data. - Part C: Listing the incumbency advantages without connecting them to the data pattern (the high rates). Students must explain the link, not just define the term. Vague answers like "incumbents are popular" do not earn the point; the response must name a concrete mechanism (franking, name recognition, fundraising, casework, or safe districts).