39.70972222, -91.39388889
Hannibal is a city along the Mississippi River in Marion and Ralls counties in the U.S. state of Missouri. According to the 2020 U.S. Census, the population was 17,312, making it the largest city in Marion County. The bulk of the city is in Marion County, with a tiny sliver in the south extending into Ralls County.
Nestled on the Mississippi River, commerce and traffic has long been a integral part of Hannibal's development, including river, rail and the interstate/highway system. Today the city is intersected by Interstate 72 and U.S. Routes 24, 36, and 61. It is across the river from East Hannibal, Illinois. Hannibal is approximately 100 miles (160 km) northwest of St. Louis (also bordering the Mississippi), 210 miles (340 km) east-northeast of Kansas City and 194 miles (312 km) miles east of Saint Joseph (both cities on the Missouri River), and approximately 100 miles (160 km) west of Springfield, Illinois.
Hannibal is not the county seat, but it has one of two county courthouses. There is also one in Palmyra, the county seat of Marion County, which is located more centrally in the county. Hannibal is the principal city of the Hannibal, Missouri micropolitan area, which consists of both Marion and Ralls counties.