First of all, Stepay, an excellent read.
Second, this is a very self-centered nation. If Americans were the best in the world at 90% of track and field events, year-in and year-out, I feel that there would more attention given to the sport.
When track and field was at its high point in this country, we were much more competetive at nearly all events. For example:
1964 Tokyo:
USA won the 100m (EWR), 200m, 400m, 5000m, 10000m, 110mH, 400mH, 4x100mR (WR), 4x400mR (WR), PV, SP, and the DT.
1968 Mexico City:
USA won the 100m (WR), 200m (WR), 400m (WR), 110mH, 4x100m (WR), 4x400m (WR). We also had the WR holder at 880y, 1500m, and one mile.
In addition to these champions, we consistently had athletes that were among the top in the world through 70s (Pre, Shorter, Rogers, Kardong, Wilkins, Wohlhuter, Scott, Liquori, Maree)
Americans aren't interested in something that they aren't the best at.