Missouri Secondary State Route Z is a east-west highway in Central Jefferson County. This runs from U.S. Rt. 61/67 to Missouri Secondary State Route A, Mapaville. MO Sec St Rt Z passes through the following town in Jefferson County. Mapaville MO Sec St Rt Z is not multi-plexed in Jefferson County. MO Sec St Rt Z intersects the following highways in Jefferson County. U.S. Rt. 61, near Pevely. U.S. Rt. 67, near Pevely. Interstate 55, near Pevely. Missouri Secondary State Route A, near Mapaville.