Chapter Two of *Give Us a Dollar and We’ll Give You Back Four (2012-13)* ($11.99 PDF, $21.95 paperback, $31.50 hardbound) gives the overall picture for 8,659 U.S. public libraries in FY2010 for each of ten metrics. I find that the 15 tables on pages 22-26 paint an interesting picture of American library funding and usage even before breaking libraries down by size.

### Circulation per capita

By my reckoning, the largest piece of calculable public library benefits is still circulation–58% of the total in my simplistic calculations. And circulation per capita correlates very strongly with funding per capita. That makes sense: Libraries with better funding are typically open more hours (so people can borrow items), have better and more contemporary collections (so people want to borrow more items) and are likely to have better displays, reader’s advisory and other features (so people are enticed to borrow items).

When you look at circulation per capita on a benchmark basis–that is, dividing libraries by the number of items circulated per potential patron–the numbers are fairly clear and compelling:

- 38% of the libraries circulate at least 10 items per capita; 25% at least 13 (that is, more than one a month)–and 6% at least 24 (at least two per month).
- As you go down in circulation per capita, the median expenditures per capita also goes down–but even faster, so that the benefit ratio (strongly based on per-cap circulation) gets lower.
- So, for example, the 24+ elite are typically well-funded (median expenditures per capita $75.82, in the top funding bracket) but also have a high benefit ratio (median 6.8). Those circulating 10-12 items per capita have median expenditures of $38.40–and median benefit ratio of 5.57. It’s a clear drop in each bracket, going down to the fortunately-small 6% of libraries circulating fewer than two items per capita: median expenditures $11.76, median benefits 4.61.

Looking at circulation from an expenditures viewpoint, the numbers are equally clear–in a manner that a graph might not show, since (as you’d expect) some libraries circulate more items relative to funding than either.

But as you move down in funding brackets from the highest ($73-$399, where median circulation per capita is 18.88 and the 75%ile is 26.65) to the lowest ($5-$11, with 2.60 median per capita circulation and 75%ile of 3.74), there’s *always*–in every one of the ten expenditure brackets–a drop for 25%ile, median, and 75%ile. But the brackets overlap, as you’d expect–e.g., the 75%ile for libraries with $53-$72 expenditures per capita (19.46) is higher than the median for $73-$399, but significantly lower than the top category’s 75%ile.

It’s a detailed version of “libraries that spend more do more” in the largest and clearest measure. If your library spends $31-$35 per capita and circulates 9 items per capita, you’re just above average for your expenditure category–and you’d be below average for libraries spending $36-$42 and in the top quartile for libraries spending $21-$25.

The numbers seem to move in two-bracket jumps–that is, the 75%ile for one spending bracket, typically 10% of the nation’s libraries, will be roughly equal to the median for two brackets higher. The 75%ile–the point at which one out of four libraries is doing better–is 7.67 for libraries spending $17-$20, where the median for libraries two brackets higher ($26-$30) is nearly identical at 7.69.

What’s that all mean? Your library can make the case that better funding, with the kind of effective spending that good public libraries should have, will lead to significantly higher use.

This post has some additional information on the book.