• Understand Basic Census Geography
  • Census tract, Block, Block Group
  • Places, county subdivision
• Understand FIPS code
• How to find GIS data: Join-table
  • CUGIR, Census Bureau, Soical Explore
• Geocoding

Beginning March 12, 2020, the public was invited to respond to the census at my2020census.gov. The 2020 Census was the first U.S. census to invite people to respond online.

• Takes place every 10 years
• 100% count of the population
• Written in US constitution, Article 1 section 2
• Since 1790, it determines the number of seats in the US house of representatives
• Data published down to census block level

The geographic entities are divided into two types: legal/administrative areas, and statistical areas.

• ZIP Code Tabulation Areas (ZCTAs) are based on the U.S. Postal Services ZIP Codes and must fall within the national boundary only. In a few cases, ZCTAs can cross into bordering states.
• School districts must fall within each state. States are responsible for updating their boundaries, and districts may cross county and place boundaries.
• County subdivisions, as the name suggests, must fall within the county. Many county subdivision names repeat throughout the nation and throughout the same state, so it is important you know which county you are working in. For example, in 2010, Beaver was used as the name of 45 different county subdivisions.

• Places stay within state boundaries. Many place names repeat throughout the country (e.g. Kansas City, Kan. vs. Kansas City, Mo. ), but each is unique, with different mayors, schools and services. In a few cases, place names can even repeat in the same state (e.g. Aaronsburg CDP in Pennsylvania occurs twice).
• Urban areas fall within the nation because they do not have to conform to place, county or even state boundaries.
• Core Based Statistical Areas (CBSAs) (metropolitan/micropolitan statistical areas) fall within the nation and often cross state lines.

• Census tracts must stay within a county and therefore a state.
• Block groups must stay within each census tract, so they must also stay within a county and state.
• Blocks fall within everything! They are the building blocks for all other geographies and therefore nest within all other geographies.

Smallest geographic census unit

• Often the same as ordinary city blocks.
• Census blocks change every decade
• Size: average about 100 people
• Can be bounded by:
  • Visible features: e.g., roads, streams, and railroad tracks
  • Invisible boundaries: e.g., property lines, city, township, school district, county limits and short line-of-sight extensions of roads.

Sibley Hall: Census Block 1035 - 361090003001035

Combination of Census Blocks and are also a subdivision of Census Tracts

• Made up of on average 40 Census Blocks.
• Smallest areas for which all sample data available (American Community Survey data)
• Size: 600 to 3000 people

Small, relatively permanent, consistent statistical divisions of a county

• Boundaries cannot across county line
• Size: Optimally contains 4,000 people; range between 1,200 and 8,000
• Approximately 65,000 census tracts in U.S.
• Tracts are designed to be fairly homogeneous with respect to demographic and economic conditions when they are first established.
• When a census tract experiences growth and the internal population grows beyond 8,000 persons, the tract is split up. This review and revision process is conducted every decade with collaboration from local planning agencies.

Incorporated Places:

• Legally bounded entity
• Referred to as cities, boroughs, towns, or villages, depending on the state
• Some form of local governance (city council, mayor, etc) recognized by the state

Census Designated Places (CDPs):

• Statistical entity
• Area with a concentration of population, housing, and commercial structures identifiable by name; not within an incorporated place

Minor Civil Divisions (MCDs):

• Legally bounded entity
• Referred to as cities, or towns
• Sub-county entities in 29 states, the District of Columbia, and Puerto Rico
• May have a local government with elected official

Census County Divisions (CCDs)

• Statistical entity
• Sub-county units that have stable boundaries and recognizable names in 21 states
• No minimum or maximum population guidelines

To undertake census data analysis and management, we need to do three things:

1. A source for the boundary files (geographic data)
2. A source for the census (attribute) data
3. Join table

• Geolode, a collaborative catalog of open geodata websites around the world.
• GIS-data-source, a clearinghouse of GIS data compiled by Keith Jenkins, GIS Librarian of Cornell University: kgj2@cornell.edu
• SimplyAnalytics, is a web-based mapping application that lets users quickly create professional-quality, thematic maps and reports using demographic, business, and marketing data for the United States.
• Openstreet map

(Reverse)-Geocoding: is the process of transforming a description of a location—such as a pair of coordinates, an address, or a name of a place—to a location on the earth’s surface.

• Cities
• Landmarks
• Business names
• Geographic locations: Mountains/Rivers
• Addresses: Street intersections/House numbers with street names/Postal codes
• Coordinates
  • Latitude and longitude
  • Values in the map document’s coordinate system
  • Military Grid Reference System (MGRS)
  • United States National Grid (USNG) system
  • Universal Transverse Mercator (UTM) coordinate notation

• A locator is a portable file used to perform geocoding across the ArcGIS platform.
• A locator can help you navigate to a specific location on the map or generate point features from tables of addresses or places.
• A locator can be fine-tuned to help return the best match results possible for your needs.

• Geocoing API Google
• Google Earth KML Data: Keyhole Markup Language