Until 1948, some streets in downtown Plano, Texas, were named Mechanic Street, Jefferson Street, Main Street, and College Street. They later became 15th Street, 14th Street, Ave K, and 16th Street. The city council passed an ordinance on November 14, 1947, to make these changes in preparation for postal service updates. In 1948, the US Post Office began delivering mail door to door in Plano, so every house had to be numbered and street signs were placed on each corner.