 In planning maps from 1947, the modern I-75 corridor was included in the system that later became the Interstate Highway System.It was also included in the "General Location of National System of Interstate Highways Including All Additional Routes at Urban Areas Designated in September 1955", or "Yellow Book" after the cover color, that was released in 1955 as the federal government readied plans for the freeway system.The Michigan Turnpike Authority (MTA), an agency which was created in 1951, proposed the construction of a toll freeway to run north–south in the state.