Hey, Old Ned - According to vintage-trek.com, Trek started making frames in 1976. I got my first one in 1978, when they were just trying to expand into the US West. The Trek sales rep offered bike shop employees very special pricing on framesets, figuring that we would sell what we rode. I got a touring geometry frame in Columbus tubing (they had run out of Reynolds tubesets), with extra braze-ons for bottles on top of and under the downtube and for rack mounts. They custom painted it for me in orange. I outfitted it in Nuovo Record, with a Campi triple chainring from a Schwinn Paramount tandem. I never liked the way the bike rode, though, as it always shimmied when loaded with touring gear. I got rid of it in a few months.
In those early days, they also had a problem with manufacturing their forks. They started with straight fork blades brazed to the crown and head tube. Then, they put the assembly in a jig and curved both blades at the same time. On my bike, that yielded blades that lined up OK at the tips, but the blade tubes had noticably different bends along their lengths. Very weird. By 1979, though, those problems were all cleared up.
Trek never had interesting paint jobs. At least in the early days, they sprayed the frames in a single color of Dupont Imron automotive paint. Functional, indeed, but not artful.
I visited the Trek factory in Waterloo Wisconsin in about 1979 since I was in the area on other business (the Chicago Bicycle Dealers Association tradeshow, I think). It was still a small operation next door to a pickle factory in that small farming town.