I gave some thought last night to the different airports/airspaces around the US and what criteria the FAA uses when designating them. I've heard of the occasional airport that gets a control tower after years of operating without one but beyond that, it seems that changes are few and far between. Examples of odd airports are Worcester (KORH) which has a control tower yet handles less than 100 general aviation flights a day with zero commercial passenger service (they did at one time have some commercial flights however anyone that lives in the area knows, airlines are not interested in going back). The airport is in the middle of the state, 25 miles from the closest outer ring of B airspace, 40 miles from the closest outer ring of C airspace, and no prohibited or restricted airspace in the vicinity of the field. Why keep a tower open there and pay for full-time controllers? Another example is John Wayne ... over 1,000 flights a day. It has to be the busiest C airport in the US and is actually busier than some B airports. Would it make more sense for that airport to be B airspace? Yeah, it's close to LAX and the airspace would become very restrictive however anyone who has flown in there - especially towards the bottom of the hour - when a dozen GA aircraft along with several commercial jets all point towards the field know it can get a little messy.