Random Samplings

U.S. Census Bureau Releases 2010 Guide to State and Local Census Geography

Written by: Katy Rossiter, Geographer, Geography Division, US Census Bureau

Have you ever wondered how many counties are in Michigan? (63!) Or, what the largest city in Wyoming is?  (Cheyenne!)  Did you know that Montpelier, Vermont has the smallest population of any state capital with just 7,855 people (as of the 2010 Census)?  All of these facts, along with many more, are available in the 2010 Guide to State and Local Census Geography recently released by the Census Bureau.  

The 2010 Guide to State and Local Census Geography is filled with geographic history, interesting facts, and important population information for each state and state equivalent.  The first Guide to State and Local Census Geography was issued in June 1993 and contained an overview of census geography and key geographic concepts for each state and state equivalents as it related to the 1990 Census.  The Census Bureau has updated this publication based on the 2010 Census and made it available as a web publication. 

Here is a peak at some of the information that the publication includes about each state and equivalents:

• 2010 Census Population
• Land Area
• Density
• Capital
• Date Became a State
• Bordering States
• International Borders
• Postal Abbreviation
• Most Populous, Largest in Area, and Most Densely Populated Areas
• Historical Centers of Population
• And many more

You can view the Guide to State and Local Census Geography for each of the state or equivalent entities. They are a great resource for understanding each state’s unique geography.  They are also a great resource for trivia night!

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Why is geography important to the Census Bureau?

Katy Rossiter, Geographer, US Census Bureau

Geography is at the heart of taking a census. The U.S. Census Bureau is tasked with counting everyone in the United States once every ten years, but we do not just count people; we count people where they live. Here are several reasons why geography is important to the Census Bureau.

The Census Bureau uses geography as the basis for taking the census.

Leading up to the decennial census, several kinds of geographic areas are delineated to aid in the collection of address information and the delivery and collection of census forms. These areas include local census offices, crew leader districts, assignment areas, and several others. Creating geographic boundaries allows us to take the census in an organized and systematic fashion. It also allows us to track our progress spatially. It ensures we cover all parts of the United States completely and as efficiently as possible.

Geography also takes on the role of ensuring we get our field workers out to everyone’s home. The Census Bureau stores all residential addresses that are included in the decennial census or on-going survey. In addition, we store all of the geographic features that need to go on a map to help field workers find all of the addresses. For the 2010 Census, and for our on-going survey work, we use both electronic and paper maps.

The Census Bureau uses geography as the basis for tabulating census data.

Data the Census Bureau collects are meaningless unless they are tied to a geographic area. Every number or statistic released by the Census Bureau relates to a specific geographic area. For instance, data users can find out the number of school-age children for the nation or for their city or even for their neighborhood. In fact, you can find data for more than 29 different geographic areas from the census blocks to counties to American Indian Reservations. Geography gives the data meaning and relevance. Visit Factfinder to learn more about available data.

The Census Bureau maintains unique geographic area boundaries that other local, state, and federal agencies use.

The Census Bureau collects, defines, and maintains boundaries for over 29 different geographic areas for our purposes, but the entities are often important to other federal, state, and local agencies as well. For example, the U.S. Small Business Administration and the U.S. Department of Housing and Urban Development use census tracts in their programs. The Census Bureau’s urban areas are used by other agencies for a variety of urban and rural programs. Furthermore, agencies utilize our boundaries for incorporated places, minor civil divisions, and counties since we update and maintain these legal boundaries from year to year.

Geography is important to the Census Bureau and census geography is a key component of the data products for decision makers and data users. Without the where, it’s all merely numbers.

Visit the Census Bureau's Geography website.

Data Visualization: Watch the Mean Center of Population move across America.

Learn more about the 2010 Census.

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What are census blocks?

Written by: Katy Rossiter, Geographer, US Census Bureau

Census blocks are:

- Statistical areas bounded by visible features such as roads, streams, and railroad tracks, and by nonvisible boundaries such as property lines, city, township, school district, county limits and short line-of-sight extensions of roads.

- The building blocks for all geographic boundaries the Census Bureau tabulates data for, such as tracts, places, and American Indian Reservations.

- Generally small in area. In a city, a census block looks like a city block bounded on all sides by streets. Census blocks in suburban and rural areas may be large, irregular, and bounded by a variety of features, such as roads, streams, and transmission lines. In remote areas, census blocks may encompass hundreds of square miles.

- A wall-to-wall coverage across the entire territory of the United States, Puerto Rico, and the Island Areas.

- Numbered uniquely with a four-digit census block number ranging from 0000 to 9999 nesting within each census tract, which nest within state and county. The first digit of the census block number identifies the block group. Block numbers beginning with a zero (in Block Group 0) are associated with water-only areas.

- Delineated by the U.S. Census Bureau once every ten years. An automated computer process looks for all visible and nonvisible features in our geographic database (MAF/TIGER) that should be a block boundary and creates a block each time those features create a polygon.

- The smallest level of geography you can get basic demographic data for, such as total population by age, sex, and race.
 

Census blocks are not:

- Delineated based on population. In fact, many census blocks do not have any population.

- Permanent throughout the decade. They may be split when a change in another geographic boundary occurs, such as an incorporated place annexation. If a block is split in between decades, a suffix will be added to the block number. For example, block 1000 would become block 1000A and 1000B.

- A boundary that can be used with American Community Survey (ACS) data. ACS data only go down to the block group level.

If you'd like to learn more, visit these links to block-related products created by the U.S. Census Bureau:

P.L. 94-171 County Block Maps – 2010 Census

Access to the 2010 TIGER/Line block Shapefiles

2010 Census Block Assignment Files

Block Relationship Files

Census Bureau Geography products

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