28,368 people (2024 Census estimate, −2.5% since 2020)
489 square miles of land · 58 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
4 active community water systems list Marion County in the area they serve, reporting 34,268 people served in all (a system that crosses county lines counts its whole population).
| MARCO RURAL WATER CO (SC3320001) groundwater · local government · SC3320001 | 17,120 served |
| GSW&SA-MARION CITY OF (SC3310001) groundwater · local government · SC3310001 | 9,104 served |
| MULLINS CITY OF (SC3310002) groundwater · local government · SC3310002 | 7,366 served |
| GSW&SA-NICHOLS TOWN OF (3310003) groundwater · local government · SC3310003 | 678 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
About 76 people were held in Marion County's jail, in Vera's latest figure (2021), or 434 per 100,000 residents ages 15–64. In 2016 it was about 115.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
1 school district has its office in Marion County. School taxes are usually the largest part of a property tax bill.
Spent $60.8 million — $59.7 million to run schools, about $15,411 per student, plus $847,000 on buildings and equipment. Money in: $12.8 million local (mostly property tax), $35 million state, $17 million federal. Long-term debt: $570,000.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Relatively Low compared with other U.S. counties. FEMA estimates natural hazards cost Marion County about $27.1 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively Low; social vulnerability: Very High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
112 bridges in Marion County: 38 in good condition, 64 fair, and 10 poor (8.9%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| SC 576 over CATFISH CANAL · built 1971 | 11,900 vehicles a day |
| US 501 SBL over LITTLE PEE DEE SWP-4 · built 1974 | 9,950 vehicles a day |
| US 76 over CATFISH BRANCH · built 1941 | 5,900 vehicles a day |
| US 76 over CATFISH BRANCH · built 1941 | 5,900 vehicles a day |
| US 301 over AGNAY SWAMP · built 1930 | 3,000 vehicles a day |
| SC 41 over BACK SWAMP · built 1930 | 2,800 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $13.3 million of work in Marion County in fiscal 2025, about $457 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
Registration deadlines, early voting and polling places for South Carolina are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Marion County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Marion County built: brayden.ozark@gmail.com.
More of South Carolina: the state government and every county in South Carolina.
Nearby counties: Florence County (21 mi) · Dillon County (21 mi) · Horry County (25 mi) · Williamsburg County (38 mi) · Darlington County (39 mi) · Marlboro County (40 mi).