In 1844, the boundaries of the county were changed slightly and the name changed to Dallas, in honor of George M. Dallas, of Pennsylvania, the Vice President-elect of the United States. During the Civil War, the courthouse was burned by Confederate raiders. More than two-thirds of the county were strong Unionists. The courthouse again burned in 1867 and 1955, with the present courthouse completed in 1958. The Methodist Episcopal denomination was organized as the first church in the county in 1839, located at a log school house in Buffalo.
Most denominations are now active in the county.
The first schools in Dallas County were of the subscription plan and in 1868 the first public common school system was inaugurated.