Missouri County Map: All 115 Counties

In 1876, St. Louis was the fourth-largest city in the United States and a booming Mississippi River manufacturing giant. Frustrated by paying taxes to support road construction in the sparsely populated rural areas of surrounding St. Louis County, city leaders lobbied for an independent charter.

At the 1875 Missouri Constitutional Convention, delegates approved the "Scheme and Charter," allowing the City of St. Louis to redraw its boundaries, absorb county powers, and secede from St. Louis County. The separation took effect in 1876, and the county seat of St. Louis County was relocated to Clayton.

While initially advantageous to the city, the fixed 62-square-mile boundary prevented post-World War II suburban annexation. Today, St. Louis County contains over 1 million residents across 88 municipalities, while St. Louis City remains physically landlocked, creating ongoing debates over regional reunification.

Under Chapter 48 of the Missouri Revised Statutes, counties are categorized based on assessed property valuation: First Class (highest valuation, including urbanized counties like Boone, Greene, and Clay), Second Class, Third Class (the vast majority of rural counties), and Fourth Class.

In standard Second and Third Class counties, administrative power is vested in a three-member County Commission. The Presiding Commissioner is elected countywide, while the First and Second Associate Commissioners represent geographic districts. Together, they supervise the county budget, road maintenance, and court facilities.

Geographically, Missouri is divided by the Missouri River: northern counties feature fertile glaciated plains and corn-soybean cultivation, while southern counties span the rugged karst topography, crystal springs, and timberlands of the Ozark Plateau.