I think what was meant is that a giant bookstore like Powell's sells many times the number of books compared to small "hole in the wall" shops. I happen to liv

I think what was meant is that a giant bookstore like Powell's sells many times the number of books compared to small "hole in the wall" shops. I happen to live in Portland not far from Powell's main store, which is huge and busy all the time. Portland also has numerous smaller shops which serve different niches and out of the way locations. I think the best metric would be number of city-wide annual book sales per capita. (r = total_annual_book_sales/population)