Map of O'Fallon, United States

O'Fallon is a city in Missouri, United States, with a population of about 85,040. It lies at 38.8106°N, 90.6998°W, about 165 m above sea level. O'Fallon is about 1,182 km (735 mi) west of Washington, D.C., the capital. The nearest city on our map is Saint Peters, 6 km to the east.

O'Fallon at a glance

Where is O'Fallon?

• The 7th largest city in Missouri on this site.
• Located in the Northern and Western hemispheres.
• Daylight ranges from about 9 h 27 min on the shortest day to 14 h 53 min on the longest day (around 21 December and 21 June).

Cities near O'Fallon

• Saint Peters — 6 km east
• Wentzville — 13 km west
• Saint Charles — 19 km east
• Chesterfield — 20 km southeast
• Wildwood — 26 km south
• Florissant — 33 km east
• University City — 38 km southeast
• St. Louis — 48 km southeast
• Oakville — 51 km southeast
• Belleville — 70 km southeast

Largest cities in Missouri

• Kansas City — 475,378
• St. Louis — 279,695
• Springfield — 170,188
• Columbia — 129,330
• Independence — 117,255
• Lee's Summit — 95,094
• Saint Joseph — 76,780
• Saint Charles — 65,794
• Blue Springs — 54,148
• Saint Peters — 52,575

Largest cities in United States

• New York City — 8,804,190
• Los Angeles — 3,820,914
• Brooklyn — 2,736,074
• Chicago — 2,664,452
• Queens — 2,316,841
• Houston — 2,314,157
• Phoenix — 1,650,070
• Philadelphia — 1,573,916
• San Antonio — 1,526,656
• Manhattan — 1,487,536

Map of United States and all its cities →

Sources: place names, coordinates, populations and time zones from GeoNames (CC BY 4.0, data retrieved October 2026). Population figures are the latest values recorded in GeoNames; depending on the country they refer to the city proper, a municipality or a wider urban area, so they can differ from census or metro-area figures. Map © OpenStreetMap contributors.