What is the ACS?
The American Community Survey (ACS) is an ongoing survey conducted by the U.S. Census Bureau. It collects detailed demographic, social, economic, and housing data annually. Unlike the Decennial Census, which counts the entire population, the ACS surveys a representative sample to estimate broader trends.
The ACS publishes two main types of estimates:
1-Year Estimates: Based on data collected in a single year.
5-Year Estimates: Pooled data from five consecutive years.
Why mySidewalk Uses 5-Year Estimates
mySidewalk curates the latest 5-Year ACS Estimates because they provide:
Greater Accuracy
Pooling five years of data reduces margins of error, especially for smaller geographic areas.
Reliable data for trends and detailed geographic breakdowns.
More Geographic Detail
Covers smaller areas like block groups, providing insights for rural and small communities.
Allows comparisons between neighborhoods, enabling targeted service and policy decisions.
Comprehensive Recency
Incorporates the latest available data, while smoothing out short-term fluctuations for stability.
Detailed Comparison: 1-Year vs. 5-Year Estimates
Feature | 1-Year Estimates | 5-Year Estimates |
Sample Size | Data from one year | Data pooled from five years |
Geographic Coverage | Large areas (65,000+ population) | Small areas (block groups and larger) |
Trend Stability | Captures recent changes; more variability | Smoothed trends over time |
Key Takeaway
5-Year Estimates are the preferred choice for reliable and granular data, especially when small geographies or long-term trends are a priority.
Common Myths About Recency
Some believe 1-Year Estimates are more recent than 5-Year Estimates. However, 5-Year Estimates include the most current year’s data within their pooled values. If a dramatic change occurred in the past year, it might be less pronounced in the 5-Year Estimates but is still reflected.
When to Use Each
1-Year Estimates: If your community experienced rapid, significant changes in the past year.
5-Year Estimates: For most use cases, especially when prioritizing accuracy or analyzing smaller geographies.
Coming in 2025
At mySidewalk, we are committed to providing the most comprehensive and useful data for your needs. To support this, we are planning two major updates to our data offerings in 2025:
Non-Overlapping 5-Year Estimates
We will introduce non-overlapping 5-Year ACS Estimates to help you track trends over time in your community.
1-Year Estimates
We will add the 1-Year Estimates, for use by larger communities and for use cases when the year-to-year trend is more important than granularity and stability.