| Tract or zip |
U.S. census tracts and five digit zip code tabulation areas (an aggregation of census blocks) were used to define the boundaries for local land-use characteristics |
| Driver status |
Driver status of respondent: licensed, not licensed, or not appropriate |
| Worker status |
Worker status of respondent: working, nonworking, or not appropriate |
| Age |
Age of respondent: 0–5 years, 6–16 years, 17–65 years, 66 years and more |
| Vehicle count |
Number of vehicles in household: 1–9 or more |
| Household size |
Household size: 1–9 or more |
| Race |
Race of the head of household: White, African American, Hispanic, other (including Asian) |
| Driver count |
Number of drivers in household: 1–6 or more |
| Personal income |
Household income divided by number of persons in household; 11 classes from $0–$100,000 or more |
| Transportation mode choice |
Transportation mode choice among motorized options, walking and biking, or transit (including buses, metro, and rail) |
| % low residential |
Low-density residential: detached single-family/duplex dwelling units, yards, and associated areas; areas of more than 90% single-family/duplex dwelling units, with lot sizes of less than 5 acres but at least half an acre (0.2 dwelling units/acre to 2 dwelling units/acre) |
| % medium residential |
Medium-density residential: detached single-family/duplex, attached single-unit row housing, yards, and associated areas; areas of more than 90% single-family/duplex units and attached single-unit row housing, with lot sizes of less than half an acre but at least one-eighth acre (2 dwelling units/acre to 8 dwelling units/acre) |
| % high residential |
High-density residential: attached single-unit row housing, garden apartments, high-rise apartments/condominiums, mobile homes, and trailer parks; areas of more than 90% high-density residential units, with more than 8 dwelling units per acre |
| % commercial |
Commercial, retail, and wholesale services; areas used primarily for the sale of products and services, including associated yards and parking areas |
| % industrial |
Manufacturing and industrial parks, including associated warehouses, storage yards, research laboratories, and parking areas |
| % vacant |
Vacant land, such as bodies of water |
| % other |
Other land uses |
| Road density index |
Liner road length over square areas, 10 classes, with a lower value indicating denser road networks |
