The primary surface to air missile defense system for the US was the Nike system. It entered service with the US Army in 1954, and overall some 240 sites were built. This site http://ed-thelen.org/loc.html has a good listing, here's the visual map. http://ed-thelen.org/pics/NikeMapUS.jpg
The original Nike, later renamed Nike Ajax to distinguish it from Nike Hercules, was rather basic, and had great room for improvement. That improvement was the Nike Hercules system. This system, which entered service in 1958 pretty rapidly replaced the Ajaxes, which were gone from regular service about 1960, and from the Guard about 1964.
Hercules decided to get around the problem of long-range accuracy and attacking formations of bombers by using a rather large hammer: It was equipped with a nuclear warhead. Close enough would be good enough. It's a little surprising, but makes some sense, to realise that the detonation is timed by a series of gears (The SF-88 site near San Francisco has a cut-away system on display). Combine this with the fact that the system, which had a multiple-stage booster, had a longer range than its predecessor, fewer sites were necessary, about 150. The sites have, of course, now all been deactivated for some 30+ years. A few have been restored, such as the afore-mentioned SF-88 just north of San Francisco, and can be visited as musea.
This site seems dedicated to 'all you never wanted to know about Nike but weren't afraid to ask' http://www.nikemissile.org/
The US Air Force, not content with having its own nuclear-missile-armed interceptors (The AIR-2 Genie under the F-106 was the main one) also decided to get in on the SAM bandwagon, they hitched their flag to the Bomarc missile. Due to budget issues, not as many of those bases were built, this site http://www.radomes.org/museum/bomarc.html indicates 11 built out of 18 which saw construction. (Plus an additional two operated in Canada). Bomarc was not an outstanding success, it was withdrawn within ten years. Most bases did not operate that long.
The continental air defense role is now filled by fighters, with only point defense targets such as the Pentagon receiving a local air defense capability, such as Avenger SAM vehicles.
