ZIP code 48421: Marathon, MI
ZIP code 48421 is in Columbiaville (11% of residents), Barnes Lake (10%) and Millers Lake (4.7%), in Lapeer County (96%) and Genesee County (3.8%), Michigan. 74% of its residents live outside city limits. It is in Michigan's 9th congressional district (96%) and Michigan's 8th congressional district (3.8%). Its state senate district is State Senate District 26; its state house district is State House District 67.
See it on the mapAll of Michigan
City and county
| City or town | Share of ZIP residents |
|---|---|
| Columbiaville | 11% |
| Barnes Lake | 10% |
| Millers Lake | 4.7% |
| County | Share of ZIP residents |
|---|---|
| Lapeer County | 96% |
| Genesee County | 3.8% |
| Town or county subdivision | Share of ZIP residents |
|---|---|
| Marathon township | 40% |
| Oregon township | 30% |
| Deerfield township | 26% |
| Richfield township | 2.9% |
| Forest township | 0.9% |
Congressional districts
| Congressional district | Share of ZIP residents |
|---|---|
| Michigan's 9th congressional district (MI-09) | 96% |
| Michigan's 8th congressional district (MI-08) | 3.8% |
This ZIP is split between districts. A mailing address in it could be in either; the map or locate_point gives the district for an exact address.
Elected officials
| Office | Member | Contact | Share of residents |
|---|---|---|---|
| U.S. Representative (MI-09) | Lisa C. McClain (R) | 202-225-2106 | 96% |
| U.S. Representative (MI-08) | Kristen McDonald Rivet (D) | 202-225-3611 | 3.8% |
| U.S. Senator | Elissa Slotkin (D) | 202-224-4822 | statewide |
| U.S. Senator | Gary C. Peters (D) | 202-224-6221 · contact form | statewide |
| State Senator (State Senate District 26) | Kevin Daley (R) | 100% | |
| State Representative (State House District 67) | Phil Green (R) | 100% |
Elected under MI's previous legislative map; the district's lines changed for 2026.
Officials serving now (members of Congress until January 3, 2027). Sources: State legislators: Open States (public domain); Members of Congress: the @unitedstates project, congress-legislators (CC0).
Local government
- Columbiaville laws: search for the Columbiaville, Michigan code of ordinances
- Barnes Lake laws: search for the Barnes Lake, Michigan code of ordinances
- Millers Lake laws: search for the Millers Lake, Michigan code of ordinances
- Lapeer County website: http://lapeercountyweb.org
- Lapeer County laws: search for the Lapeer County, Michigan code of ordinances
- Genesee County website: http://www.gc4me.com
- Genesee County laws: search for the Genesee County, Michigan code of ordinances
State legislative districts
| State senate district | Share of ZIP residents |
|---|---|
| State Senate District 26 | 100% |
| State house district | Share of ZIP residents |
|---|---|
| State House District 67 | 100% |
Voting precincts
6 voting precincts overlap ZIP 48421. Map them, with each precinct's share of the ZIP's residents.
Get this in your AI agent
Your agent can get these cities, counties, districts and precincts with their shares, and their GeoJSON boundaries, from Boundary Atlas. Add https://atlas-production-d344.up.railway.app/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
related_geographies(id="us:zcta:48421")
ZIP 48421 here is the Census Bureau's ZIP Code Tabulation Area, which approximates the USPS ZIP Code; PO-box-only ZIPs have none. Districts are the maps in force for the November 3, 2026 election.