O'Fallon, Illinois
O'Fallon is a city in St. Clair County, Illinois, with 32,306 residents in 2020. It spans 2 congressional districts: IL-12 (69%) and IL-13 (31%). It spans 3 state senate and 4 state house districts.
County
| County | Share of residents |
|---|---|
| St. Clair County | 100% |
Congressional districts
| Congressional district | Share of residents |
|---|---|
| Illinois's 12th congressional district (IL-12) | 69% |
| Illinois's 13th congressional district (IL-13) | 31% |
Elected officials
| Office | Member | Contact | Share of residents |
|---|---|---|---|
| Mayor | Eric Van Hook | 618-624-8730 | citywide |
| U.S. Representative (IL-12) | Mike Bost (R) | 202-225-5661 | 69% |
| U.S. Representative (IL-13) | Nikki Budzinski (D) | 202-225-2371 | 31% |
| U.S. Senator | Richard J. Durbin (D) | 202-224-2152 · contact form | statewide |
| U.S. Senator | Tammy Duckworth (D) | 202-224-2854 · contact form | statewide |
| State Senator (State Senate District 57) | Christopher Belt (Democratic) | 618-875-1212 | 69% |
| State Senator (State Senate District 56) | Erica Harriss (R) | 618-307-5789 | 22% |
| State Senator (State Senate District 55) | Jason Plummer (R) | 618-283-3000 | 9.8% |
| State Representative (State House District 114) | Kevin Schmidt (R) | 618-215-1050 | 48% |
| State Representative (State House District 112) | Katie Stuart (Democratic) | 618-365-6650 | 22% |
| State Representative (State House District 113) | Jay Hoffman (Democratic) | 618-416-7407 | 21% |
| State Representative (State House District 109) | Charlie Meier (R) | 618-651-0405 | 9.8% |
Officials serving now (members of Congress until January 3, 2027). Sources: Mayors: Open States (public domain); State legislators: Open States (public domain); Members of Congress: the @unitedstates project, congress-legislators (CC0).
Local government
- O'Fallon website: http://www.ofallon.org/
- O'Fallon laws: search for the O'Fallon, Illinois code of ordinances
- St. Clair County laws: search for the St. Clair County, Illinois code of ordinances
State legislative districts
| State senate district | Share of residents |
|---|---|
| State Senate District 57 | 69% |
| State Senate District 56 | 22% |
| State Senate District 55 | 9.8% |
| State house district | Share of residents |
|---|---|
| State House District 114 | 48% |
| State House District 112 | 22% |
| State House District 113 | 21% |
| State House District 109 | 9.8% |
ZIP codes
Percentages mark ZIPs only partly in O'Fallon: the share of that ZIP's residents living in it.
Get this in your AI agent
Your agent can get O'Fallon's counties and districts with shares, its ZIP codes (level='zcta'), and its boundary as GeoJSON (get_boundaries). Add https://boundarymcp.com/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
related_geographies(id="us:place:1755249")
O'Fallon here is the Census Bureau's place boundary as of January 1, 2025. Shares are of 2020 Census population. Districts are the maps in force for the November 3, 2026 election.