Things to keep in mind when using the ACS 2004 tabulations just released. The new table designs are those that should be in place for the 2005 ACS. There will be many "CTPP-like" tables as part of the "subject" tables. ACS went into "full implementation" of data collection in January 2005. In 2004, the ACS data collection was limited to 1203 counties (approximately 1/3 of total U.S. counties) and these counties are biased toward those with more than 250,000 population. See map and list of counties for 2003 ACS data collection: http://www.census.gov/acs/www/SBasics/county02.htm
BE CAREFUL if you are planning to make comparisons with 2000 Census data. The NCHRP 08-48 project will include information on "bridging" between 2000 Census data and ACS, but it is not yet available. It is better to compare ACS 2000 to ACS 2004 data (apples to apples), as is done in the multi-year profile sheet that Chuck Purvis mentioned. "Journey to work" characteristics are included in the Economic page.
Other differences:
The 2004 ACS does not include group quarters population.
ACS collects data over all twelve months of the year and has different residence rules than decennial census. Therefore, areas with high seasonal population variation are more likely to see differences between decennial and ACS results.
General differences:
Average journey-to-work travel times are about 1 minute lower in ACS than in Census 2000.
For example:
U.S. Total
Census 2000: 25.5 minutes
Census 2000 (1203 counties) : 25.1 minutes
ACS 2000 : 24.4 minutes
This chart shows the ACS average travel time for the U.S. total.
Year LowBound UpBound Estimate
2000 24.2 24.6 24.4
2001 24.1 24.5 24.3
2002 24.2 24.6 24.4
2003 24.2 24.4 24.3
2004 24.6 24.8 24.7
The decennial census also reported a greater proportion of households without vehicles.
U.S. Total
Census 2000: 10.2 percent
Census 2000 (1203 counties): 10.5 percent
ACS 2000: 9.4 percent
The decennial census consistently has more workers who select "carpool" as their mode to work.
U.S. Total
Census 2000: 12.2 percent carpool
Census 2000 (1203 counties): 11.9 percent carpool
ACS 2000: 11.2 percent carpool
We examined these same characteristics for 6 test ACS counties (which had larger sample sizes than the national sample), with similar results.
The "new" table added that I like is B08134 "Means of Transportation by Travel Time" which is MUCH more useful than the table from previous ACS tabulation which had "public transit" and "Other" as the 2 means of transportation categories. This version has 8 detailed means of transportation, and 9 categories of travel time.
The Census Bureau told the AASHTO SCOP Census Data Working Group (chaired by Jonette Kreideweis) at the August 22 meeting, that they would include tabulations by PLACE OF WORK from ACS as part of their standard product. Hurrah! These tables were shared as DRAFT with the CTPP listserv in May and presented at the TRB Census Conference in Irvine.
Elaine Murakami
FHWA Office of Planning
