In most of my nearly 60 years in this hobby, I've had to travel around to find raceways, so I get to see and follow them over time. A major factor is real estate prices and whether the track owner rents or owns. Big cities tend to have commercial property owned by huge commercial real estate corporations that seem to not care if their prices mean large numbers of vacancies. Smaller communities often have real estate owned by local individuals that appreciate having property rented at a discount over standing idle for a higher amount, and this same scenario is sometimes found in larger cities as well. Discounted commercial space near a population center is a significant factor. In conversations with raceway owners, I find this is often a deciding factor as to why they've continued to exist. Another major factor is having additional income besides simply a slot car raceway. Two raceways I'm familiar with in California are hobby stores and have a significant business in R/C models. Several I've known have some level of arcade game business. Some survive by selling on the internet, often with the raceway primarily to meet the requirements necessary to buy from slot car distributors. Others manufacture or distribute slot car product in addition to the raceway. There are also those cases where the raceway owner is a diehard enthusiast and subsidizes the raceway's existence through other business or professional means. These are the primary factors I've found for raceways that have stayed around more than a year or two.
I've also seen several situations where, when slot racing was having one of its 'up' periods, a successful raceway would suddenly induce several other raceways to open in the same vicinity. Unless these additional raceways are serving different niches, for example, one caters to big raceway track enthusiasts and the other to hard plastic scale model racing on smallish flat tracks, then very often the multiple raceways in the area siphon off enough of each others' business that none survive. I've seen this happen multiple times. I've also seen situations where private clubs form around garage or basement tracks and similarly siphon off racers that prefer a particular niche or variant that isn't well served by a raceway that needs to appeal to a larger market.
Unfortunately, we slot racers are sometimes to blame. I've seen multiple situations where the local racers could not agree on a common rule set or class of car, or if they did, the rules were seriously abused to the point that the group seriously fractured and the raceway couldn't keep a large enough faction of any of them to be successful.
And finally, outside forces have profound effects. After all, slot racing is a hobby dependent on people spending their discretionary time and income to participate. In an America with a short attention span demanding frequent re-invention of anything to stay viable and popular and with an abundance of things for us to spend our discretionary time and income doing, keeping a sufficient clientele together over an extended period is a huge challenge. In just this forum, I regularly see people selling their equipment because they've lost a job, been forced to change jobs, had a serious illness, or some other reason that they can no longer continue. And then us old diehards are slowly, one by one, leaving this world forever.
It's a tough world for raceways. I sincerely appreciate every raceway owner, wish you the very best for continued success, will support you whenever I can, and sincerely understand when the conditions you face prevent you from continuing. I wish this weren't so, and slot racing was once again so popular there were hundreds of raceways all thriving across the country.