Just to give a sense of scale here --- all but two of these pix are from a single parade, the Mystic Krewe of Nyx (a couple are from Ancient Druids, the first parade that rolled that night) ---
Nyx alone, the all-female krewe celebrating just its fifth year, involves some 23 thousand people, and they have a waiting list of several thousand more in the wings. Their parade pictured here included 39 floats. That's just one krewe, and there are I believe almost 50 krewes that parade at some point, just in the city limits alone over the season, not counting the neighboring burbs. Not all of them are that big but put together it's a massive spectacle.
Normally a New Orleanian takes one of two approaches: either (a) immerse yourself in it totally and thoroughly, or (b) get the hell out of town until it blows over. Usually when I lived there I took the latter route but came down just for this one event. It was a lot of work, but went well -- still, I'm glad to be out of there.