The vast majority of funds for roads and schools are state, county, and city.

For example, Michigan has a public school budget of $13.9 billion of which $1.8 billion is Federal.

So if Paul was elected and eliminated the DoE Michigan would lose 1.8 billion a year in Federal aid. Or ~$180 per citizen per year. So the state could tax each citizen $180 a year to make up for that loss. Or they could revise their budget. After a point, there is no correlation between spending and quality of education. It is such a relatively small amount of money the state could raise sales tax by .006% and cover that loss two-fold.

As for roads, almost every road is maintained by cities and counties. Property tax pays for roads. The DoT gives money to the state to help maintain the interstates, select bridges, ports, and rail-lines, but again, compared to the state budget, the amount of our money that we get back is only a drop in the bucket. States could easily make up that cost. Like education, this would only come out the be $150 per person in Michigan.

The post office was subsidized 5.5 billion last year. They deliver 515 million packages a day, or 187,975,000,000 items a year. If they raise the cost of postage by 3 cents they could cover that subsidy

Loans for college? That is what banks are for. The federal government shouldn't act as a bank and I think we can all see the unintended consequences of their educational loans. Graduation rates are falling, prices are rising, personal debt is increasing, defaults are increasing, and University of Phoenix exists. The country is much worse off because of federal subsidized student loans. Get rid of the whole program altogether.

So Save $25,000 a year in federal taxes, then pay ~$500 more in state taxes, and everything is the same. Where did the rest of the money go?

The problem with federal agencies is that no matter how efficient they are, they are net-negative. No matter what, less money will eventually go back to the states. And the money (which was ours in the first place) always comes with stipulations. Federal highway funding comes with a few, you have to have a drinking age of 21, your max speed has to be lower than 75 mph, your minimum DUI limit must be a .08. So the feds take our money, then only give (a portion) of it back if we do what they say. These decisions should be up to the state, and the duty of providing roads should be up to the state.

So when you say "get used to a reduced level of service" I really don't know what services you are talking about? International foreign aid? Billion dollar contracts with Lockheed martin, Northrop Grumman, and Halliburton? Because my schools, roads, police, fire, libraries, etc. are all paid for with local property, income, and sales tax. Only a very small fraction is from the feds, so small that if it were taken away all the state would have to do is raise sales tax by a half of a percent and we would have more money than before.