The folks over at City Observatory have recently developed something called The Storefront Index.
It is a mapping of “clustered” consumer-facing storefront businesses across the 51 largest cities in the United States and within a 3-mile radius of their CBD. (Their definition of cluster is that the business is located within 100m of another business.)
At the top of this list is New York (no surprise here) with 9,905 storefronts and at the bottom of this list is Detroit (probably no surprise here either) with 411 storefronts. On average, they found that the “typical” city has about 900 storefronts within this 3-mile radius.
Here’s a screenshot of New York:
And here’s a screenshot of Detroit:
They should be at the same scale.
If you’d like to read their Storefront Index Report, you can do that here. And if you’d like to explore their interactive maps, you can do that here. City Observatory has made all of this available as a free tool for city builders – which is really great to see. (You can even download their shapefiles if you’re into that sort of thing.)