The 1942 highway system was dominated by the US Highway routes. There were no freeways in Texas in 1942; the first freeway in Texas was Houston's Gulf Freeway in September 1948, and the first section of Central Expressway in Dallas opened on August 20, 1949. Humble Oil is now ExxonMobil

Compared to the 1950 map, this 1954 Humble map greatly expanded coverage of the DFW and Houston metropolitan areas.

The Chevron map has less detail in the urban areas compared to the Humble map.

This is a city street map for both Dallas and Fort Worth.

As of Spring 1965 the Interstate Highway System was approximately 50% complete.

By the late 1960s, many oil company map covers were becoming very plain. Of course, by the early 1970s most oil companies stopped providing free highway maps.

This 1972 Houston map was issued by the Houston Chamber of Commerce, which explains the "City of Tomorrow" designation

The great freeway-building binge of the 1960s was over, but there were still plenty of missing links and unbuilt freeways that would need to wait for funding in an era of greatly diminished resources for highway construction. As highway construction slowed, my observation is that map companies updated their maps less frequently and therefore maps were more susception to error. However, this 1973 Exxon map is quite accurate.