Method
Counts of total households and households by monthly housing cost are acquired from the U.S. Census Bureau’s American Community Survey (ACS). Data represent estimates for the 5 year period 2017-2021. Mapped data are summarized to 2021 census tract boundaries. The data for monthly housing costs as a percentage of household income are developed from a distribution of “Selected Monthly Owner Costs as a Percentage of Household Income” for owner-occupied and “Gross Rent as a Percentage of Household Income” for renter-occupied units. The owner-occupied categories are further separated into those with a mortgage and those without a mortgage. Indicator statistics are measured as a percentage total households using the following formula:
[Households with Costs Exceeding 30% of Income] / [Total Households] * 100
For more information on the data reported in the American Community Survey, please see the complete American Community Survey 2021 Subject Definitions.
Background
The American Community Survey (ACS) is a nationwide survey designed to provide communities with reliable and timely social, economic, housing, and demographic data every year. The ACS has an annual sample size of about 3.5 million addresses, with survey information collected nearly every day of the year. Data are pooled across a calendar year to produce estimates for that year. As a result, ACS estimates reflect data that have been collected over a period of time rather than for a single point in time as in the decennial census, which is conducted every 10 years and provides population counts as of April 1. The Census Bureau combines 5 consecutive years of ACS data to produce estimates for geographic areas with fewer than 65,000 residents. These 5-year estimates represent data collected over a period of 60 months. Because the ACS is based on a sample, rather than all housing units and people, ACS estimates have a degree of uncertainty associated with them, called sampling error. In general, the larger the sample, the smaller the level of sampling error. Data users should be careful in drawing conclusions about small differences between two ACS estimates because they may not be statistically different.
For more information about this source, including data collection methodology and definitions, refer to the American Community Survey data users website.