This polygon shapefile contains Comprehensive Housing Affordability Strategy (CHAS) data at the geographic summary level 080 (State - County - County Subdivision - Place/Remainder - Tract). The CHAS is derived from the American Community Survey (ACS) data, which has a smaller sample size than the Decennial Census (which was the basis of the 2000 CHAS). As a result, the Census Bureau cannot produce data using only one year of survey responses, except in very populous areas. For areas with population 65,000 or greater, ACS estimates are available each year using only the most recent year’s survey responses (known as "1-year data"). For areas with population 20,000 or greater, ACS estimates are available each year based on averages of the previous three years of survey responses ("3-year data"). For areas with population less than 20,000—including all census tracts, and many places, counties, and minor civil divisions—the only ACS estimates available are based on averages of the previous five years of survey responses ("5-year data"). The primary purpose of the CHAS data is to demonstrate the number of households in need of housing assistance. This is estimated by the number of households that have certain housing problems and have income low enough to qualify for HUDs programs (primarily 30, 50, and 80 percent of median income). It is also important to consider the prevalence of housing problems among different types of households, such as the elderly, disabled, minorities, and different household types. The CHAS data provide counts of the numbers of households that fit these HUD-specified characteristics in HUD-specified geographic areas. In addition to estimating low-income housing needs, the CHAS data contribute to a more comprehensive market analysis by documenting issues like lead paint risks, affordability mismatch, and the interaction of affordability with variables like age of homes, number of bedrooms, and type of building. This layer is intended for researchers, students, policy makers, and the general public for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production. This layer will provide a basemap for layers related to socio-political analysis, statistical enumeration and analysis, or to support graphical overlays and analysis with other spatial data. More advanced user applications may focus on demographics, urban and rural land use planning, socio-economic analysis and related areas (including defining boundaries, managing assets and facilities, integrating attribute databases with geographic features, spatial analysis, and presentation output.) United States. Department of Housing and Urban Development. (2016). ACS 5 Year CHAS Data by Summary Level 080, 2008-2012. United States. Department of Housing and Urban Development. Available at http://purl.stanford.edu/rc622nx6841.