Glossary

Benchmark

The period in time when the geographic data was snapshotted for use / return by the Census Geocoder API.

Census Block

The single smallest element in the core geographic hierarchy is the Census Block. This is the most granular geographical area for which the US Census Bureau reports data, and is the smallest geographic unit where data is available for 100% of its resident population.

Census Data

This is information that is collected from the Constitutionally-mandated decennial census, which collects information from 100% of residents in the United States.

Centroid Latitude

The latitude coordinate for the geometric center of a geographic area.

Centroid Longitude

The longitude coordinate for the geometric center of a geographic area.

Internal Point Latitude

The Census Bureau calculates an internal point (latitude and longitude coordinates) for each geographic entity. For many geographic entities, the internal point is at or near the geographic center of the entity. For some irregularly shaped entities (such as those shaped like a crescent), the calculated geographic center may be located outside the boundaries of the entity. In such instances, the internal point is identified as a point inside the entity boundaries nearest to the calculated geographic center and, if possible, within a land polygon.

Internal Point Longitude

The Census Bureau calculates an internal point (latitude and longitude coordinates) for each geographic entity. For many geographic entities, the internal point is at or near the geographic center of the entity. For some irregularly shaped entities (such as those shaped like a crescent), the calculated geographic center may be located outside the boundaries of the entity. In such instances, the internal point is identified as a point inside the entity boundaries nearest to the calculated geographic center and, if possible, within a land polygon.

Forward Geocoding

Also known as geocoding, a process that identifies a specific canonical location based on its street address.

Geocoding

The act of determining a specific, canonical location based on some input data.

See also

• Forward Geocoding

• Reverse Geocoding

Geography

A geographical area. Corresponds to a layer and represented in the Census Geocoder as a GeographicArea.

Layer

When working with the Census Geocoder API (particularly when getting geographic area data), you have the ability to control which types of geographic area get returned. These types of geographic area are called “layers”. Which layers are available is ultimately determined by the vintage of the data you are retrieving.

See also

• Geographies in the Census Geocoder > Benchmarks, Vintages, and Layers

One-line Address

A physical / mailing address represented in a single line of text, like '4600 Silver Hill Rd, Washington, DC 20233'.

Parametrized Address

An address that has been broken down into its component parts. Thus, a single-line address like '4600 Silver Hill Rd, Washington, DC 20233' gets broken down into:

• STREET: '4600 Silver Hill Rd'

• CITY: 'Washington'

• STATE: 'DC'

• ZIP CODE: '20233'

Reverse Geocoding

A process that identifies a specific canonical location based on its precise geographic coordinates (typically expressed as latitude and longitude).

Sampled Data

Data reported by the US Census Bureau that is derived from data collected from a subset of the resident population (i.e. from a surveyed sample of potential respondents).

Tigerline

Tigerline and Shapefiles represent the GIS data that defines all of the features (places) and geographical areas (polygons) that comprise the mapping data for the Census Geocoder API.

Vintage

The census or survey data that the geographic area meta-data returned by the Census Geocoder API is linked to, given that geographic area’s benchmark.