American Community Survey (ACS)

ACS is an ongoing survey that gathers detailed population and housing data every year. It replaced the long form of the Census.

Average Block Size

Calculated in acres, Average Block Size is the average size of all the blocks making up a given block group. It is determined by dividing the total land area in a block group by the number of blocks in the block group.


A Census Block is the smallest geographic unit used by the Census Bureau for the tabulation of data collected from all households.

Block Group

A subdivision of a Census Tract, a Block Group is the smallest geographic unit for which the Census Bureau tabulates sample data.

Bus Rapid Transit (BRT)

BRT is an enhanced bus system that combines the flexibility of buses with the efficiency of rail. It operates on bus lanes or other transitways, providing significantly better service than traditional bus lines.

Center for Transit Oriented Development (CTOD)

A joint venture between the Center for Neighborhood Technology, Reconnecting America and Strategic Economics, CTOD is dedicated to providing best practices, research and tools to support market-based transit-oriented development.

Census Transportation Planning Package (CTPP)

CTPP is a set of tabulations from the long form of the decennial census demographic surveys designed for transportation planners.

Federal Transit Administration (FTA)

FTA is one of 11 operating administrations within the U.S. Department of Transportation. FTA provides stewardship of combined formula and discretionary programs to support a variety of locally planned, constructed, and operated public transportation systems throughout the U.S. (

FTA New Starts

New Starts is FTA's discretionary program that serves as the Federal government's primary financial resource for supporting locally-planned, implemented, and operated capital investments in fixed guideway transit. (

FTA Small Starts

Small Starts is a subset of FTA's New Starts program that funds lower cost projects. To qualify the requested amount of New Starts funds must be under $75 million and the total project cost under $250 million. Small Starts are eligible for a simplified evaluation and ratings process.

Final Design

Final Design (FD) is the third phase of the New Starts planning and development process, and includes the preparation of final construction plans, detailed specifications and bid documents.

Fixed Guideway (Route) Transit

Heavy rail, light rail, commuter rail, streetcars, trolley buses, bus rapid transit (with dedicated right of way) and cable cars.

Full Funding Grant Agreement (FFGA)

An FFGA is the final step of the New Starts planning and project development process. FTA and sponsors of New Starts projects enter into this multi-year contractual agreement that formally establishes the maximum level of Federal financial assistance and outlines the terms and conditions of Federal participation. The final step for Small Starts is a Project Construction Grant Agreement (PCGA).

Housing Costs

Housing Costs reported in the Housing + Transportation Affordability Index (H+T® Index), represent the average cost of housing for a given block group. Using Census data, they are calculated as an average of Selected Monthly Owner Costs and Gross Rent factoring the percentages of owner occupied housing units with a mortgage and renter occupied housing units with cash rent. (

Local Employment Dynamics (LED)

LED is a voluntary partnership between state labor market information agencies and the U.S. Census Bureau to develop new information about local labor market conditions.

Longitudinal Employer-Household Dynamics (LEHD)

LEHD is a program within the U.S. Census Bureau that combines federal and state administrative data on employers and employees with core Census Bureau censuses and surveys.

Metropolitan Statistical Area (MSA)

A geographic entity defined by the federal Office of Management and Budget for use by federal statistical agencies, based on a core area with a large population nucleus, plus adjacent communities having a high degree of economic and social integration with that core. Qualification of an MSA requires the presence of a city with 50,000 or more inhabitants, or the presence of an Urbanized Area (UA) and a total population of at least 100,000 (75,000 in New England). (

Preliminary Engineering

Preliminary Engineering (PE) is the second stage of the New Starts planning and development process. During this phase, local project sponsors consider their design options to refine the locally preferred alternative and complete the National Environmental Policy Act (NEPA) process. In addition, during the PE phase of project development, local sponsors finalize management plans, demonstrate their technical capabilities to develop the project, and commit local funding sources.

Project Development

Also called Alternative Analysis, Project Development (PD) is the first phase the New Starts funding timeline. Local project sponsors are required to perform an alternatives analysis that evaluates the mode and alignment options for a particular corridor in the community.

Public Transportation (Transit)

As defined in the Federal Transit Act, Public Transportation is "transportation by a conveyance that provides regular and continuing general or special transportation to the public, but does not include school bus, charter, or intercity bus transportation or intercity passenger rail transportation." (

Residential Acre

Residential Acres are defined as the land area of all blocks in which gross density (households per land acre) is greater than one.

Residential Density

Residential Density represents household density of residential areas, in contrast to population density on land area. Blocks (within block groups) are selected on the criteria that gross density (households per land acre) must be greater than one. From these selected blocks, both households and land acres are aggregated to the block group level, at which level residential density is calculated as households per residential acre.


Composed of Block Groups, a Census Tract is a small, relatively permanent statistical subdivision of a county.

Transit Region

Transit Regions are aggregated from one or more Census County boundaries that contain the majority of the region's transit system. Using counties allows for more consistency when aggregating data with different geographical bases (e.g. TIGER 2000, TIGER 2009, TIGER 2010, etc.).

Transit Shed

The transit Shed is the half (or quarter mile) buffer around all transit stations in a region, of a specific transit agency, or of a specific transit line. It is the aggregate of transit zones. Since many transit zones overlap, data cannot simply be aggregated from individual transit zones. Aggregating data to transit sheds prevents the double counting that would occur if data from individual transit zones was aggregated.

Transit Zone

A transit zones is the half mile buffer around each transit station. One half mile (radius) is considered a walkable distance. The TOD Database also offers the option to choose a one quarter mile buffer for an analysis of the immediate station area.

Transportation Costs

Household Transportation Costs as reported by the Housing + Transportation Affordability Index, include auto ownership costs, auto use costs, and public transit costs. (