Smithville is a city in Clay and Platte counties in the U.S. state of Missouri and is part of the Kansas City metropolitan area, along the Little Platte River. The population was 8,425 at the 2010 United States Census.
Smithville is located in western Clay County on the Little Platte River. The Little Platte is dammed just east of the city to form the Smithville Reservoir. U.S. Route 169 passes the west side of the city.
According to the United States Census Bureau, the city has a total area of 15.67 square miles (40.59 km2), of which 15.56 square miles (40.30 km2) is land and 0.11 square miles (0.28 km2) is water.
Smithville is named after Humphrey "Yankee" Smith (1774 – May 5, 1857) after he settled at the site in 1822. The town was originally known as "Smith's Mill" but ultimately became "Smithville" as it was easier to pronounce. Another reputed history behind the name is that it was going to be named Smith's Mill, but there was already another current settlement in Missouri with the same name so it was altered slightly to differentiate it.
Silver Screen stars Wallace Beery and Noah Beery, Sr. were born and raised near Smithville.
The Aker Cemetery and Downtown Smithville Historic District are listed on the National Register of Historic Places.
As of the census of 2010, there were 8,425 people, 3,115 households, and 2,321 families living in the city. The population density was 541.5 inhabitants per square mile (209.1/km2).