How many college bookstore distributors in the US?

There's no definitive, publicly available list of *all* college bookstore distributors in the US. The number is also fluid, as companies merge, acquire others, or go out of business.

The distribution network is complex. Some large publishers have their own distribution arms, while others use independent distributors who work with multiple publishers and supply bookstores of various sizes. Many bookstores also source materials from multiple distributors and even directly from publishers.

Therefore, it's impossible to give a precise number. You would likely find dozens, if not hundreds, of entities involved in the distribution process at various levels.