Pants still seem to have clearly fallen out of favor in the late nineteenth and early twentieth centuries.
I conjecture in this case that New Yorkers took to wearing pants in the 1860s, and then the trend descended to the flyover states, every ma and pa wearing them. So the City renounced them. Until pants fell out of favor in the backwaters, and were reclaimed by the City in the 1970s.
Or maybe it only works for food.