A taxing history
We had an income tax during the Civil War, then it was declared unconstitutional by the Supreme Court in 1895. Then the income tax came back in 1913 and that sets up the modern income tax as we know it today. One of the reasons that historians think we pay in the spring was at one point taxes were levy, mostly on the rich, and the rich started to get out of town for the summer in the spring, so the government wanted to collect taxes in the spring before rich people skip town.