I have to put my vote in for Illinois. BITD you had all the major game companies either with development centers there (Williams, Bally/Midway, Taito, Atari, Gottleib/Mylstar, Rock-ola and Sega) and there were arcades everywhere and every bar (and there are a sh*tload of bars in Chicago) had 4 to 5 games plus a shufflebowler and a couple of pins. There were over 60 arcades on the approved testing list for Williams games, just in the Chicago area. And another 45-50 bars that were approved test sites.
The survival of classic machines in any particular area has a lot to do with the demographics of the operators in the area. The Chicago area had a lot of corporate chain arcades (Aladdin's Castle, PinPan Alley, mall arcades) and when the going got tough the games went to auction. In California (and most of the rest of the country) there were more route operators and these guys would make the people on Hoarders look tame. What you are seeing now in a lot of the country is these guys have finally decided that $30 a month in storage fees = 6 packs of smokes and they would rather have the smokes or the operator's heirs just got the bill from the storage company and went "WTF?!?" and dumped the contents.
Back in the early 80's there was a gaming auction house (not unlike SuperAuctions today) in Gary, Indiana (just south of Chicago) that liquidated a ton of the arcades and the warehouses full of games in Chicago. A friend went down to one of the auctions and found a Robotron (IIRC) to bid on. He won the auction for something stupid like $27 (or maybe it was $25 + 10% sellers commission). When he went to pay, the clerk asked if he needed help and my friend said "No. I can get one machine out by myself" at which point the clerk gave him a funny look and said "it's not one machine, you bought 1 row of machines". It took him 3 trips to get all 18 machines out before the warehouse closed that night. All but 2 or 3 of the games worked when plugged in. He said that while he was moving the last load, they had 10 dumpsters lined up outside the loading dock doors and the warehouse guys were lining the unsold games up, smashing them and throwing them into the dumpsters. He stopped to chat and was told he could have anything there for free, just haul it away. When he asked how many were being destroyed, the guy said about 15 to 20 rows didn't sell (15 x 18 = 270, 20 x 18 = 360). This company held auctions every 2 months and the guy destroying the machines said that auction was typical. Oh the humanity...
ken