You can find examples of century old warehouse districts in just about any city that had +100k residents prior to WWII.
In Jax, the Riverside Warehouse District (people call it CoRK Arts District now) is probably worth looking at. You won't find any tech startups in it but has successfully transformed from a 1920s industrial district anchored by a furniture maker, a bottling plant and dairy into one filled with two craft breweries with popular tap rooms, millwork/lumber shops, a large arts complex, and an exotic foods company. The mix of stuff in the warehouses filled with arts stuff is pretty interesting as well. There's +100,000SF of stuff ranging from furniture makers, screen printers to blacksmiths and glass makers.
Some others I'm familiar with that may be worth checking out include the Channel District (Tampa), Shockoe Bottom (Richmond), the Design District (Miami), Castleberry Hill (Atlanta).
I also second Chris' comment. The Midwest is full of large scale examples in various states. Places like Kansas City, Cleveland, Minneapolis, Omaha, etc. would be great places for a study on warehouse districts.