[2] The county was organized November 16, 1820, and named for Daniel Ralls, Missouri state legislator.

Ralls County was one of several along the Mississippi River settled in the early years primarily by European-American migrants from the Upper South, especially Kentucky and Tennessee.

They brought slaves and slaveholding traditions with them, and quickly started cultivating crops similar to those in Middle Tennessee and Kentucky: hemp and tobacco.

Ralls is considered one of the counties in the outer ring of what is called the Little Dixie region.

Historically, the Democratic Party predominantly controlled politics at the local level in Ralls County.

Republicans now hold the office of Sheriff, Coroner, and Western District Commissioner.