Our local area, though much smaller than Gary, has had many of the same problems. Our area has always been manufacturing and agriculture. When a factory shuts down, the local economy suffers, and other businesses go under as well.
Within a 20 mile radius we've had several manufacturers close up:
Nabisco - Closed - 100% of workers out of a job
Westclox - Closed - 100% of workers out of a job
Union Carbide/American Hoechst - Closed - 100% of workers out of a job
Borg-Warner - Closed - 100% of workers out of a job
Snap-On Tools - Closed - 100% of workers out of a job
Sundstrand - Closed - 100% of workers out of a job
Material Services - Closed - 100% of workers out of a job
Thatcher Glass - Closed - 100% of workers out of a job
L.O.F. Glass/Pilkington - Closed 1 of 2 plants - 60-70% of workers out of a job
There have been several factories and manufacturers that have either shut-down or drastically downsized, also.
The point is that if folks aren't working and earning a living, they also aren't spending money at the local businesses, which causes those businesses to go under, too. Most of the local 'downtown' areas around here look just like the pix of Gary. All kinds of halfway decent buildings are sitting empty. Although the 'thrift' stores are doing pretty good!!! Many of the communities are even 'landscaping' there downtowns.....trees, shrubs, flowers, and that sort of thing.....but there still aren't any businesses!
Our downtown isn't quite a bleak as some of the others. Most of our buildings have tenants. There are alot of 'mom & pop' businesses, and a sh*t load of antique and nicknack shops, and of course office space.
It looks like for our area, things are on the 'up-swing' again, as there are several manufacturers and mega-warehouses starting to come in. Being in the I-80/I-39 corridor, outside of the congestion of Chicago and the 'burbs, and having access to not only those Interstates, but also to railroads and river transportation, MAYBE
this area will pull out of it's economic nose-dive before it ends up completely like Gary!
One of the up-sides to a nearly deserted downtown, is that you can find a parking spot directly in front of just about any business that is still open!