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County ZIP codes · South Carolina · FIPS 45011

Barnwell County, SC ZIP Codes

Barnwell County, South Carolina has 8 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026): 7 residential and 1 for PO boxes or a single organization. 4 of the residential ones lie mainly in Barnwell County and 3 mainly in a neighboring county; 6 cross the county line. Median household income ranges from $41,579 in 29817 (Blackville) to $51,870 in 29812 (Barnwell) (Census Bureau, ACS 2020-2024).

  • ACS2020-24
  • Census2020

Where are the ZIP codes of Barnwell County?

29812 · Barnwell: $52k29817 · Blackville: $42k29826 · Elko: –29836 · Martin: –29843 · Olar: $36k29849 · Ulmer: $90k29853 · Williston: $45k2981229853298172983629843298492982629812 · Barnwell: $52k29817 · Blackville: $42k29826 · Elko: –29836 · Martin: –29843 · Olar: $36k29849 · Ulmer: $90k29853 · Williston: $45k29812298532981729836298432984929812 · Barnwell: $52k29817 · Blackville: $42k29826 · Elko: –29836 · Martin: –29843 · Olar: $36k29849 · Ulmer: $90k29853 · Williston: $45k298122985329817298362984329849
The residential ZIP codes of Barnwell County (whole outlines, including the parts in neighboring counties), shaded by median household income in national fifths (ACS 2020-2024).<$54.1k$98.1k+no figure

Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).

How different are its ZIP codes?

They carry 7 postal town names: Barnwell, Williston, Blackville, Olar, Martin, Ulmer, Elko.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).

All 7 residential ZIP codes in Barnwell County

4 ZIP codes lie mainly in Barnwell County; 3 more reach into it from a neighboring county and follow the first table.

Residential ZIP codes mainly in Barnwell County, largest first; "In this county" is the share of the ZIP's land in the county
In this county
29812 Barnwell 11,132 64 $52k $113k 98%
29853 Williston 5,944 49 $45k $107k 75%
29817 Blackville 4,139 36 $42k $84k 84%
29826 Elko 241 119 – $79k 100%

Partly in Barnwell County

Residential ZIP codes mainly in another county that reach at least 1% into Barnwell County, by their share here
In this county
29849 Ulmer 271 7 $90k $161k 27%
29843 Olar 934 14 $36k $78k 19%
29836 Martin 326 3 – $108k 17%

Download the 8 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; county shares by land area (Census 2020 ZCTA-county relationship file).

Which ZIP codes cross the county line?

6 ZIP codes of Barnwell County extend into another county. A ZIP code follows mail routes, not county borders.

Share of each ZIP code's land in Barnwell County and in the neighboring counties
ZIPIn BarnwellElsewhere
2981298%Allendale County2%
2985375%Aiken County25%
2981784%Bamberg County16%
2984319%Bamberg County81%
2983617%Allendale County83%
2984927%Allendale County73%

Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).

PO Box and single-organization ZIP codes

ZIP codes in Barnwell County without a residential area (GeoNames postal codes)
ZIPPostal name
29813Hilda

Source: GeoNames postal codes (CC BY 4.0).

Which first three digits do Barnwell County's ZIP codes use?

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Every ZIP code of Barnwell County starts with 298.

Three-digit prefixes of Barnwell County's ZIP codes, the sectional center for each (USPS labeling list L005, effective October 1, 2026) and how many of the prefix's codes are Barnwell County's
PrefixSectional centerHereAll codes
298Augusta, GA (SCF 308)844

Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.