In preparation for this week's webinar, you learned about the geographic areas the Census Bureau uses to tabulate and disseminate data. This week, you’ll explore the Census Bureau in greater detail. The Census Bureau is part of the U.S. Department of Commerce. The mission of the Census Bureau is to “serve as the leading source of quality data about the nation's people and economy.” To fulfill its data gathering objectives, the Bureau conducts both decennial censuses and a continuous survey known as the American Community Survey (ACS). The ACS was born in 2005 out of a need for more up-to-date information than the decennial census provided. Data from both the decennial census and the ACS are made available in a variety of ways, one of the most popular of which is the via the American FactFinder site.
Take a look through the American Community Survey Information Guide which the Census Bureau updated in December 2017.
Data collected by the Census Bureau serve some critical functions. These data are used to:
- determine the number of seats each state has in the house of representatives;
- distribute over 400 billion dollars in federal funding annually;
- make planning decisions about community services.
Geography and GIS are very important to the Census Bureau.
Watch this brief presentation on the Maps of the US Census Bureau (5 minutes) by Atri Kalluri, Assistant Division Chief of the US Census Bureau.
Census data have long been applied to transportation planning and research. Today, there are a number of emerging sources of data which serve to compete with or complement the role of the census data in these fields. Read this 2017 paper by Gregory D. Erhardt (University of Kentucky) and Adam Dennett (Centre for Advanced Spatial Analysis, University College, London) which examines this topic.
Census Transportation Planning Products Program
The Census Transportation Planning Products Program (CTPP) is an initiative led by the American Association of State Highway and Transportation Officials (AASHTO). AASHTO is an organization we’ll take a closer look at in an upcoming lesson. The CTPP provides special tabulations of Census data which are of particular interest to transportation planners. These datasets provide insight into how people commute and which modes of transportation they use. They are often used to validate travel demand models which themselves are used to make decisions on what types of transportation projects are needed to support regional needs, including those related to economic growth, public health, transit needs, and highway safety issues (for a quick overview of the Four Step Model (FSM) which commonly used in travel demand modeling, see this 2007 article by Michael McNally at the University of California, Irvine).
To facilitate the use of the CTPP data, AASHTO created a web-based application to examine travel flows. The CTPP even has a YouTube channel devoted to teaching people how to use the software (although the quality of the videos is less than stellar). Take a look at the YouTube video below (5 minutes) which shows how to generate some basic county to county commuter flow data. The CTPP data analysis tool also has the ability to display results in a variety of formats including thematic maps.
Another interesting use of the commuter flow data can be seen in an application created by Mark Evans. Mark used the Google Maps API to create a GIS application called Commuter Flows which facilitates the visualization of census tract level commuter flows derived from the ACS data.