I think the "green" you referred to has more to do with the color of money than any environmental considerations. Almost all of the older race tracks [ not just drag strips ] were built in places where the land was relatively cheap. As populations grow these places have more value for other types of development. Also once these areas build up people start complaining about the noise and traffic on race days. In most parts of the country racing is a 7-9 month sport. Track owners still have some expenses during the off season, but no income so it's not surprising that when land values & taxes start rising track owners think about selling out. Another factor is the changing of the public's interests. Quite simply, as a country we have reduced interest in motorsports. We don't have the same "car culture" we once did. I am not saying that people don't care about cars and racing, just that like other activities that were once more popular the interest is declining. One look at most race venues, car shows & cruises shows a rather dispiriting percentage of 50+ people. It's not all gloom & doom. There are still enough of us and places to race to have a good time and who knows maybe the next generation will rediscover the same excitement we did when we first "got into " cars & racing.