Not much happens. People in their 20s are hung over from their New Year's Eve parties. Families sleep late and might take the children to a park. Businesses are usually closed New Year's Day. Some gas stations and restaurants are open. Most people go back to work on January 2. Most students go back to school on the first Monday after January 1.

Generally, not a lot, since the celebrations usually happen on New Year's Eve, which is the night before New Year's Day. Most people are hungover from the previous night's partying and drinking and spend the day recovering before they have to return to work. Most businesses are closed New Year's Day anyway.

there are usually parties. people drink a lot and wear nice clothes. and at midnight people usually drink champagne maybe they throw a lot of confetti. in some of the bigger US cities there are fireworks too. usually the parties arent formal in that there isn't a dinner or food or anything like that. maybe just snacks and a lot of alcohol.