Lessons
Quick reference
Landmark cases, federal laws, people, formulas, key numbers, and the pairs people mix up, all on one page.
A one-page review of the cases, laws, people, formulas, and numbers that come up again and again. It's a memory aid, not a substitute for the lessons: each section links to the lesson that explains the reasoning. It's built for the final weeks before your exam.
Landmark cases
Zoning, due process, and equal protection
| Case | Year | Holding in brief | Lesson |
|---|---|---|---|
| Welch v. Swasey | 1909 | Building height limits that differ by district upheld | Land use law |
| Hadacheck v. Sebastian | 1915 | A brickyard could be barred from an area that had turned residential, despite the loss in value | Land use law |
| Buchanan v. Warley | 1917 | Racial zoning is unconstitutional | Settlement |
| Village of Euclid v. Ambler Realty | 1926 | Comprehensive zoning is a valid use of the police power | Land use law |
| Gorieb v. Fox | 1927 | Front setback requirements upheld | Land use law |
| Nectow v. City of Cambridge | 1928 | Zoning can be invalid as applied to one parcel | Land use law |
| Shelley v. Kraemer | 1948 | Courts can't enforce racially restrictive covenants | Settlement |
| Village of Belle Terre v. Boraas | 1974 | Limits on the number of unrelated people in a household upheld | Land use law |
| Young v. American Mini Theatres | 1976 | Dispersing adult theaters upheld | Land use law |
| Moore v. City of East Cleveland | 1977 | A narrow definition of related family struck down | Land use law |
| Village of Arlington Heights v. Metropolitan Housing | 1977 | Equal protection claims require proof of discriminatory intent | Land use law |
| City of Cleburne v. Cleburne Living Center | 1985 | Special permit for a group home failed even rational basis review | Land use law |
| City of Renton v. Playtime Theatres | 1986 | Adult uses may be regulated for their secondary effects | Land use law |
| City of Edmonds v. Oxford House | 1995 | A "family" definition isn't an occupancy limit exempt from the Fair Housing Act | Housing |
| Village of Willowbrook v. Olech | 2000 | "Class of one" equal protection claims are allowed | Land use law |
| Reed v. Town of Gilbert | 2015 | Content-based sign rules get strict scrutiny | Land use law |
| Texas Dept. of Housing v. Inclusive Communities Project | 2015 | Disparate-impact claims are allowed under the Fair Housing Act | Housing |
| City of Austin v. Reagan National Advertising | 2022 | An on-premises/off-premises sign distinction isn't automatically content-based | Land use law |
Takings and exactions
| Case | Year | Holding in brief |
|---|---|---|
| Pennsylvania Coal v. Mahon | 1922 | A regulation that goes "too far" is a taking |
| Berman v. Parker | 1954 | Public purpose, including aesthetics, supports eminent domain |
| Penn Central v. New York City | 1978 | Three-factor balancing test; judge the parcel as a whole |
| Agins v. City of Tiburon | 1980 | Two-part takings test, including "substantially advances" (later rejected in Lingle) |
| Loretto v. Teleprompter Manhattan CATV | 1982 | Permanent physical occupation is a per se taking |
| Hawaii Housing Authority v. Midkiff | 1984 | Redistributing land to break up concentrated ownership is a public use |
| First English Lutheran Church v. Los Angeles County | 1987 | Compensation is owed for temporary takings |
| Nollan v. California Coastal Commission | 1987 | Exactions need an essential nexus |
| Lucas v. South Carolina Coastal Council | 1992 | Loss of all economic use is a per se taking (nuisance exception) |
| Dolan v. City of Tigard | 1994 | Exactions must be roughly proportional |
| Palazzolo v. Rhode Island | 2001 | Buying after a regulation doesn't bar a takings claim |
| Tahoe-Sierra v. Tahoe Regional Planning Agency | 2002 | Moratoria aren't per se takings |
| Kelo v. City of New London | 2005 | Economic development can be a public use |
| Lingle v. Chevron | 2005 | "Substantially advances" is a due process test, not a takings test |
| Koontz v. St. Johns River Water Management District | 2013 | Nexus and proportionality apply to denials and money demands |
| Murr v. Wisconsin | 2017 | Multi-factor test for defining "the parcel" |
| Knick v. Township of Scott | 2019 | Takings claims can go straight to federal court |
| Cedar Point Nursery v. Hassid | 2021 | Government-granted physical access is a per se taking |
| Sheetz v. County of El Dorado | 2024 | Legislative fees aren't exempt from Nollan/Dolan |
Full explanations: Takings, exactions, and property rights.
State cases the exam likes
| Case | State | Holding in brief | Lesson |
|---|---|---|---|
| Golden v. Planning Board of Ramapo | New York, 1972 | Phased growth tied to public facilities upheld | Growth management |
| Fasano v. Board of County Commissioners | Oregon, 1973 | Site-specific rezonings are quasi-judicial | Rezonings |
| Construction Industry Ass'n v. City of Petaluma | 9th Circuit, 1975 | An annual cap on building permits upheld | Growth management |
| Mount Laurel decisions | New Jersey | Developing towns must provide a realistic opportunity for their fair share of regional affordable housing | Housing |
Federal laws and programs, in order
| Year | Law or program | Remember it for |
|---|---|---|
| 1785 | Land Ordinance | Rectangular survey: 6-mile townships of 36 one-square-mile sections |
| 1922–1928 | Standard State Zoning and Standard City Planning Enabling Acts | Model laws most states copied |
| 1934 | National Housing Act | Created the FHA and insured mortgages |
| 1937 | Housing Act | Public housing |
| 1949 | Housing Act | Urban renewal (Title I) |
| 1954 | Housing Act | Section 701 planning grants |
| 1956 | Federal-Aid Highway Act | Interstate system and the Highway Trust Fund |
| 1962 | Federal-Aid Highway Act | The "3C" urban transportation planning process |
| 1964 | Civil Rights Act, Title VI | No discrimination in federally funded programs |
| 1966 | National Historic Preservation Act | National Register, SHPOs, Section 106 |
| 1966 | Model Cities | Coordinated antipoverty efforts |
| 1968 | Fair Housing Act | Housing discrimination banned; amended in 1988 to add disability and familial status |
| 1968 | National Flood Insurance Act | The NFIP |
| 1970 | National Environmental Policy Act | EIS for major federal actions |
| 1970, 1990 | Clean Air Act (major amendments) | Nonattainment and transportation conformity |
| 1972 | Clean Water Act | Section 404 wetland permits |
| 1972 | Coastal Zone Management Act | State coastal programs |
| 1973 | Endangered Species Act | Listed species and critical habitat |
| 1974 | Housing and Community Development Act | CDBG and Section 8 |
| 1975 | Home Mortgage Disclosure Act (HMDA) | Public mortgage lending data by neighborhood and race |
| 1976 | Resource Conservation and Recovery Act (RCRA) | Solid and hazardous waste, including landfill standards |
| 1976 | HUD Code | Federal construction standard for manufactured homes |
| 1977 | Community Reinvestment Act (CRA) | Banks must serve their whole service areas, including low- and moderate-income neighborhoods |
| 1980 | CERCLA (Superfund) | Contaminated site cleanup and liability |
| 1986 | Low-Income Housing Tax Credit | The largest source of new affordable rentals |
| 1988 | Stafford Act | Federal disaster declarations |
| 1990 | Americans with Disabilities Act | Accessible facilities, programs, and communication |
| 1990 | NAGPRA | Return of Native American remains and cultural items |
| 1991 | ISTEA | Stronger MPOs, flexible transportation funding |
| 1992 | HOPE VI | Distressed public housing replaced with mixed-income communities |
| 1996 | Telecommunications Act | Local cell tower siting, within federal limits |
| 1998, 2005 | TEA-21, SAFETEA-LU | Continued ISTEA's multimodal approach |
| 2000 | Disaster Mitigation Act | FEMA-approved local hazard mitigation plans |
| 2000 | RLUIPA | Protection for religious land uses |
| 2010 | Choice Neighborhoods | Succeeded HOPE VI; housing plus neighborhood investment |
| 2012 | MAP-21 | Performance-based transportation planning |
| 2015 | FAST Act | Continued the MAP-21 framework |
| 2017 | Opportunity Zones | Capital gains incentives in low-income tracts |
| 2021 | Infrastructure Investment and Jobs Act (IIJA) | Bipartisan Infrastructure Law: the largest infrastructure investment in decades |
| 2022 | Inflation Reduction Act | Clean energy and climate programs, largely through tax credits |
More: Federal laws and programs that shaped planning.
People and ideas
| Person | Remember them for |
|---|---|
| Pierre L'Enfant | 1791 plan for Washington, D.C. |
| James Oglethorpe | Savannah's wards around public squares (1733) |
| Baron Haussmann | Boulevards of Second Empire Paris |
| Frederick Law Olmsted (and Calvert Vaux) | Central Park; Riverside, Illinois |
| Jacob Riis | How the Other Half Lives, tenement reform |
| Daniel Burnham | 1893 Chicago exposition, City Beautiful, 1909 Plan of Chicago |
| Ebenezer Howard | The Garden City and its greenbelt |
| Clarence Perry | The neighborhood unit, centered on an elementary school |
| Clarence Stein and Henry Wright | Radburn: superblocks and cul-de-sacs |
| Lewis Mumford | Regional Planning Association of America |
| Alfred Bettman | The Euclid amicus brief |
| Rexford Tugwell | The New Deal greenbelt towns |
| Le Corbusier / Frank Lloyd Wright | Radiant City (towers in the park) / Broadacre City (an acre per family) |
| Robert Moses | Large-scale public works in New York |
| Jane Jacobs | The Death and Life of Great American Cities, "eyes on the street" |
| Ian McHarg | Design with Nature, overlay suitability analysis |
| Kevin Lynch | The Image of the City: paths, edges, districts, nodes, landmarks |
| William H. Whyte | How people use small urban spaces |
| Walter Christaller | Central place theory |
| Johann Heinrich von Thünen / William Alonso | Rings of land use around a market / urban bid-rent |
| Charles Tiebout | Households "vote with their feet" among local governments |
| Jean Gottmann | Megalopolis, the Boston–Washington corridor |
| Ernest Burgess / Homer Hoyt / Harris and Ullman | Concentric zones / sectors / multiple nuclei |
| Joel Garreau | Edge cities |
| Donald Shoup | The High Cost of Free Parking: the costs of parking minimums |
| Jarrett Walker | The transit ridership vs. coverage tradeoff |
| Richard Florida | The Rise of the Creative Class |
| Gordon Cullen | Townscape, serial vision |
| Andreas Faludi | Procedural (theory of) vs. substantive (theory in) planning |
| Herbert Simon | Bounded rationality and satisficing |
| Charles Lindblom | Incrementalism, "muddling through" |
| Amitai Etzioni | Mixed scanning |
| Morris Hill / Nathaniel Lichfield | Goals-achievement matrix / planning balance sheet |
| Carl Patton and David Sawicki | Basic Methods of Policy Analysis and Planning |
| Paul Davidoff | Advocacy planning |
| Sherry Arnstein | The ladder of citizen participation |
| James Fishkin | Deliberative polling |
| Norman Krumholz | Equity planning in Cleveland |
| John Friedmann | Transactive planning; later radical planning |
| Leonie Sandercock | Insurgent, multicultural planning (Towards Cosmopolis) |
| John Forester, Judith Innes, Patsy Healey | Communicative and collaborative planning |
| Susan Fainstein | The just city: equity, diversity, democracy |
| Horst Rittel and Melvin Webber | Wicked problems |
| Roger Fisher and William Ury | Getting to Yes, interest-based negotiation, BATNA |
| Bruce Tuckman | Forming, storming, norming, performing (adjourning added later) |
| Irving Janis | Groupthink |
| Kenneth Thomas and Ralph Kilmann | Five conflict styles: competing, accommodating, avoiding, compromising, collaborating |
| Henry Martyn Robert | Robert's Rules of Order (1876) |
| John French and Bertram Raven | Five bases of power: legitimate, reward, coercive, expert, referent |
| John Kotter | Eight steps for leading change, starting with urgency |
| Daniel Goleman | Emotional intelligence |
| Abraham Maslow | Hierarchy of needs |
| Frederick Herzberg | Hygiene factors vs. motivators |
| Douglas McGregor | Theory X and Theory Y |
More: Planning history, Planning theory.
Formulas
| What | Formula |
|---|---|
| Floor area ratio | Floor area ÷ lot area |
| Stories (even floors) | FAR ÷ lot coverage |
| Lot coverage | Footprint ÷ lot area |
| Gross density | Units ÷ total site area |
| Net density | Units ÷ (site area − streets, open space, other non-residential land) |
| Parking | Floor area ÷ 1,000 × spaces per 1,000 sq ft |
| Trip generation | Units (or floor area) × trip rate |
| Cost burden | Annual housing cost ÷ annual gross income |
| Affordable monthly housing cost | Annual income × 0.30 ÷ 12 |
| Share of area median income | Household income ÷ AMI |
| Location quotient | (Local industry share of jobs) ÷ (national industry share of jobs) |
| Shift-share | National growth + industry mix + local (competitive) share |
| Economic base multiplier | Total employment ÷ basic employment |
| Retail capture rate | Local sales in a category ÷ trade-area spending in it |
| Dependency ratio | (Under 15 + 65 and over) ÷ ages 15–64 × 100 |
| Linear projection | Add the same amount each period |
| Geometric projection | Apply the same rate each period |
| Housing-unit method | Units × occupancy rate × household size |
| Households from population | Population in households ÷ average household size |
| Housing units needed | Households ÷ (1 − vacancy allowance) |
| Present value | Future value ÷ (1 + r)^t |
| Benefit-cost ratio | PV of benefits ÷ PV of costs |
| Percent change | (New − old) ÷ old |
| Compound annual growth rate | (End ÷ start)^(1 / years) − 1 |
| Constant (today's) dollars | Past value × (CPI today ÷ CPI then) |
| Z-score | (Value − mean) ÷ standard deviation |
| Chance of at least one event over n years | 1 − (1 − annual chance)^n |
| Earned value variances | Schedule variance = EV − PV; cost variance = EV − AC |
Worked examples: Implementation math, Population and economic analysis, Statistics.
Numbers worth memorizing
| Number | Meaning |
|---|---|
| 43,560 | Square feet in an acre |
| 640 | Acres in a square mile |
| 50,000 | Urbanized-area population that requires an MPO |
| 30% / 50% | Cost-burdened / severely cost-burdened share of income |
| 30% / 50% / 80% of AMI | Extremely low / very low / low income (HUD) |
| 1% | Annual chance of the "100-year" (base) flood; about 26% over 30 years |
| 0.2% | Annual chance of the "500-year" flood |
| ¼ to ½ mile | Typical walking radius for TOD and neighborhood parks |
| 68 / 95 / 99.7 | Percent of a normal distribution within 1 / 2 / 3 standard deviations |
| 90% | Confidence level of ACS margins of error |
| About 400 | Random responses for roughly ±5 points at 95% confidence (large population) |
| 4× | Sample size needed to halve a margin of error |
| 65,000 | Minimum population for ACS 1-year estimates |
| 170 questions, 3.5 hours, ~74 seconds each | The exam |
| 20% | Federal historic rehabilitation tax credit for income-producing buildings |
| 5 years | Typical hazard mitigation plan update cycle |
| 32 credits every 2 years | AICP certification maintenance, historically |
Commonly confused pairs
| These two | The difference |
|---|---|
| Comprehensive plan vs. zoning ordinance | Long-range policy guide vs. the regulation that implements it |
| Goal vs. objective vs. policy | Broad end state vs. measurable target vs. commitment that guides decisions |
| Variance vs. conditional use | Relief from a rule because of hardship vs. a listed use allowed if it meets standards |
| Area variance vs. use variance | Dimensional relief vs. allowing an unlisted use (banned in many states) |
| Legislative vs. quasi-judicial | Making general policy vs. applying rules to one property (findings, record, no ex parte contact) |
| Facial vs. as-applied challenge | The law is invalid everywhere vs. invalid for this property (Euclid vs. Nectow) |
| Procedural vs. substantive theory | How planning decisions are made vs. the things being planned (Faludi) |
| Filtering vs. gentrification | Aging housing moves down the income ladder vs. higher-income residents move into lower-income areas |
| HMDA vs. CRA | Lenders disclose mortgage data vs. banks must serve low- and moderate-income areas |
| Eminent domain vs. regulatory taking | Taking title with compensation vs. regulation so burdensome it counts as a taking |
| Contract zoning vs. conditional zoning | A bargain that surrenders the police power vs. conditions attached to a rezoning |
| TDR vs. PDR | Development rights sold on a private market vs. bought with public funds |
| Inclusionary vs. incentive zoning | Requires affordable units vs. offers a bonus for any public benefit |
| GO bond vs. revenue bond | Backed by taxing power vs. repaid by the project's own revenues |
| Funding vs. financing | Where the money ultimately comes from vs. spreading the cost over time by borrowing |
| TIF vs. special assessment | Captures growth in property tax vs. charges properties for a special benefit |
| Zoning vs. covenants | Public rules the city enforces vs. private deed restrictions owners or an HOA enforce |
| Fairly debatable vs. substantial evidence | Court's test for legislative decisions vs. for quasi-judicial ones |
| Tax abatement vs. PILOT | Reduces or freezes the tax vs. replaces it with a negotiated payment |
| Land bank vs. community land trust | Returns vacant property to use vs. holds land permanently for affordability |
| RFQ vs. RFP | Qualifications first vs. approach and (usually) price |
| MOU vs. intergovernmental agreement | Records intentions, often not binding vs. a binding contract between governments |
| Schedule variance vs. cost variance | EV − PV (behind if negative) vs. EV − AC (over budget if negative) |
| Output vs. outcome measure | Work produced vs. results in the community |
| Logic model order | Inputs → activities → outputs → outcomes → impact |
| Validity vs. reliability | Measures the right thing vs. measures it consistently |
| Needs assessment vs. asset mapping | Starts from a community's gaps vs. from its strengths |
| Cross-sectional vs. longitudinal | Many cases at one time vs. the same cases over time |
| Nominal vs. ordinal | Categories with no order vs. ordered categories |
| Type I vs. Type II error | False positive vs. false negative |
| Percent vs. percentage points | 10% to 12% is a 20 percent rise vs. a 2-point rise |
| Large-scale vs. small-scale map | Small area in detail (1:1,200) vs. large area, little detail (1:1,000,000) |
| Mediation vs. arbitration | A neutral helps the parties agree vs. a neutral decides |
| Hygiene factor vs. motivator | Prevents dissatisfaction (pay, policies) vs. creates satisfaction (achievement, responsibility) |
| Transformational vs. transactional leadership | Motivates through vision and development vs. through exchange of rewards |
| BATNA vs. ZOPA | Your best option if talks fail vs. the range where both sides' acceptable deals overlap |
| Random-sample survey vs. deliberative polling | What people think now vs. what they think after learning and discussing |
| Quorum vs. majority vote | Members needed present to act vs. votes needed to pass a motion |
| Public hearing vs. public meeting | Formal, noticed, creates the record vs. informal, for ideas and information |
| LOS vs. VMT | Driver delay vs. the amount of driving |
| Ridership vs. coverage | Frequent service where riders are vs. thin service everywhere |
| Indirect vs. induced effects | Supplier spending vs. workers' household spending |
| Riparian vs. prior appropriation | Reasonable use by streamside owners (East) vs. first in time, first in right (West) |
| Rent control vs. rent stabilization | Caps rents at a set level vs. limits annual increases |
| ESA Section 7 vs. Section 10 | Consultation for federal actions vs. incidental take permits with an HCP for others |
| Climate mitigation vs. adaptation | Cutting emissions vs. preparing for expected impacts |
| EA vs. EIS | Determines significance (may end in a FONSI) vs. full analysis for significant effects |
| National Register vs. local historic district | Largely honorific for private owners vs. binding review of changes |
| Aspirational principles vs. Rules of Conduct | Ideals, not enforceable alone vs. enforceable standards |
| AICP Code vs. government ethics law | Professional standard for certified planners vs. statutes binding public officials; follow the stricter |