Business planning by county
Mason County, Illinois
Use a county reference when organizing a market-research brief, outreach territory or business calculation. County population gives geographic context; it does not measure the number of qualified customers.
Identify the right place
Mason County is a county or county equivalent in Illinois. Its five-digit FIPS code is 17125; preserve the leading zero when storing county codes as text. The Gazetteer lists 24.23 square miles of water and a representative point at 40.236993, -89.913575. That point identifies the geography; it is not a street address or a site boundary.
Open this county in Census data · Download this county as JSON
Business planning by county checklist
- Define who the offer is for before selecting an area.
- Distinguish residents, businesses and potential customers in the calculation.
- Keep source dates and assumptions attached to your working file.
These are geographic reference records, not contact lists or verified sales leads.
Sources and interpretation
Geography: 2025 U.S. Census Gazetteer. Population: Vintage 2025 estimates, July 1, 2025. County equivalents include parishes, boroughs, independent cities and planning regions. Puerto Rico population is not supplied by this population file.
Population is an estimate, not a live count. Gazetteer land and water measures describe the geographic area; they do not measure service availability, households, businesses or market demand. Match the FIPS code and source vintage when joining another dataset.
More county references in Illinois
- Marshall County
Illinois · FIPS 17123
11,473 residents · 2025 estimate
- Massac County
Illinois · FIPS 17127
13,502 residents · 2025 estimate