In the late 1950s and early 1960s, Naval Aviation concentrated on the low level nuclear strike mission. Navigation in the era before GPS was usually a matter of compass headings and stopwatch, backed up by visual orientation with local landmarks.
A couple of notes. First, back in 1960, there weren’t really any such things as “low level routes.” Pretty much all airspace was available for use. Note as well that the altitudes used were a good deal lower than allowed today. Next, do note that this is pretty much the best example of the Skyhawk paradigm around. Meticulous planning to the target, not one word about getting home.