It rained less back then, I think there were less trees because it was a drier era. Look at NYC's rainfall total from 1966, which was one of only two years in which NYC had 4 100+ days (the other was 1953-- in the same era) In 1966, NYC only had 26 inches of rain, nowadays we get that in a few months lol. LGA hit 107 in 1966 exceeding the 106 that NYC hit in 1936 (also in the same era.)