Mongomery County is the first county that U.S. Rt. 41A comes into on the north end of Tennessee. This is also the only county in Tennessee that U.S. Rt. 41A has a by-pass route. U.S. Rt. 41A passes through the following town. Clarksville U.S. Rt. 41A is multi-plexed in Mongomery County Tennessee State Route 12, at Clarksville. U.S. Rt. 79, at Clarskville.