Since nobody else has mentioned it yet, you'd have to throw out the name Buck Perry and his spoonplugs/spoonplugging. Buck is credited with coining the term "structure" along with several others still commonly in use. The spoonplug, which was developed and patented back in the mid 1940s, were a series of metal crankbait equivalents for lack of a better description, each designed to run in a very specific depth range regardless of speed. The smallest size ran as shallow as 2 feet, while the largest ran up to 25' on a pre-stretched monofilament line called "No-Bo." If you ran them on wire line, which Buck also made for his lures, you could easily reach 40'-60' of depth. By following a defined protocol of fishing from the shallows to deep, you could find all types of structure such as ledges and channels, points, humps, roadbeds, etc. This was also all before there was what we consider "pros," at least if you define pros as organized and recognized tournament angling which arguably began in 1968-1969 with the formation of B.A.S.S. and their national tourney circuit. By then, flashers were well popularized and available, and paper graphs were soon to follow.
-T9