This chapter addresses users of the decennial census long-form sample who want to know, in general terms, what benefits—and challenges—the new American Community Survey (ACS) presents to them. The chapter first summarizes the basics that every user should know about the ACS and key ways in which it is similar to and differs from the decennial census long-form sample. It then addresses two central issues: (1) why users should care about the ACS in terms of the benefits it offers and (2) some of the challenges those benefits present for users. Finally, it offers the panel’s assessment of the value of the ACS to users based on the available knowledge about its properties.

To work with data from the ACS, users should be acquainted with the following features of its design and operations: the population or universe covered, rules for assigning people to a place of residence, questionnaire content and reference periods, sample size and design, data collection procedures, data products, and data-processing procedures to generate the products. The key factor to keep in mind is that, unlike the census long-form sample, the ACS is continuous: a fresh sample of addresses is surveyed every month, and data products represent cumulations of monthly data for 1-year, 3-year, and 5-year periods. The discussion below pertains to the ACS