Conclusion on Using the ACS for Transportation Planning

While transportation planners face significant challenges in using ACS data for applications for which they have previously used the long-form sample, the frequency of release of updated ACS estimates offers benefits to them. The 1-year and 3-year period estimates can help transportation planners track overall trends in commuting patterns and other aspects of household transportation and alert them to the need for special surveys or other data collections to update their models. The 5-year estimates can provide intercensal checks on local-area transportation patterns that would not be possible with the decennial long-form sample, although estimates for traffic analysis zones will often need to be combined to attain an acceptable level of precision. The ACS PUMS can be used in a variety of ways, and it is issued more frequently than the long-form-sample PUMS.


Researchers in universities, colleges, research institutes, and other settings have made extensive use of long-form-sample data to understand key social processes, such as migration flows, changes in marriage patterns and family living arrangements, and the social and economic effects of the aging of the population. They have also used long-form-sample data to develop insights on such important topics as trends in educational attainment, magnitudes and effects of immigration from abroad, and concentrations of people in poverty.

Some research applications have used summary files of detailed tabular data for small areas, such as Summary Files 3 and 4 from the 2000 census. For example, summary files have supported analyses of migration flows among regions, states, counties, and places and of concentrated populations of the poor, minorities, and immigrants from different countries. Summary information on neighborhood characteristics has been appended to the records of respondents to such ongoing research surveys as the Panel Study of Income Dynamics. This additional information has permitted rich contextual analyses of family social and economic dynamics.

Other research applications have used the PUMS files, which have been constructed for most censuses back to 1850 (Ruggles, 2000). PUMS files permit detailed, multivariate analyses on such topics as the interactions among disability, educational attainment, labor force attachment, and income and the characteristics that distinguish people who migrate long distances from those who migrate shorter distances or not at all.

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