[tanaros]

Assuming the numbers I linked above are correct or at least in the ballpark:

At the federal level, pretty much anything else, since it’s already not really spending any money on libraries, relatively speaking.

At the state/local level, it’s harder to say since there are many more administrative units involved, each with their own budget and operating model. (This also makes it hard to optimize in general, since you’d have to apply the optimizations independently across many polities.)

If I use my city as an example, library funding is 5% of the city budget. The state provides no funding to any library, so this is the entire amount the libraries get. It’s the second smallest spend by category as the city tracks such things —- though there is an “other” category that represents 10% of the budget. The bulk of the spending is on police (23%), fire (17%), and public works (11%). Obviously these are also critical services (basically everything in the city budget is!), so it’s not easy to do cost cutting there either, but there’s proportionally more room for improvement.

[librarian-guy]

Data have shown time and time again that for every dollar spent on a public library the community return on investment is four $4 dollars. Public libraries are more efficient and effective the more they are used. The more a book is checked out the more people have enjoyed it or learned from it. Also, where else can you go without being forced to spend money? A lot of people can't afford these materials, just like they could not afford to pay for their own security (police) or put out fires by paying for private firefighters. Also, most libraries make up less than 5% of their municipal budgets, often closer to 1% in big cities. Seems like a good investment to me.