On August 21, 1923, SH 20 in the new highway system was routed over the previously proposed Highway 20A from Fredericksburg to Austin and then over the proposed Highway 20 to Hempstead as a second class highway. The old route to Leander was cancelled, and northwest of there became part of SH 43 when it was extended southwest. In 1924, the state highway department assumed responsibility to maintain all state highways which were previously maintained by the counties. The following year, state lawmakers vest the department with the authority to acquire right of way, survey, plan, and build highways. On August 10, 1925, SH 20 was given a third class extension to Kerrville. On February 20, 1928, SH 20 was given an auxiliary route SH 20A from Fredericksburg to a point on the highway between Kerrville and Junction. All of the highway from Fredericksburg to Hempstead was classified as a "secondary federal highway". The portion between Fredericksburg and Kerrville along with the new auxiliary route were classified as "state highways" eligible for state aid only.