In 1976, just one top 30 U.S. airport was connected to a commuter rail or subway line - Logan Airport in Boston. Since then, JFK, Newark, Reagan National, Atlanta, Phoenix, Minneapolis, LAX, SFO, Midway, Philly, O'Hare, BWI, Miami, Fort Lauderdale, and DFW have all been hooked into local rail lines, and the Sea-Tac stop on Seattle's light rail system is scheduled to open later this year. Portland and Oakland also have rail links, but both just miss being in the top 30 for enplanements. Dallas Love is also out of the top 30, and its DART stop should open in 2010.
Yesterday's announcement that the FTA will fund the DC Metro Dulles extension, puts that airport in line for a station sometime between 2015 and 2017. This will represent the 18th top 30 airport with a rail link, or 60% of the total, and assuming Seattle makes its December 2009 forecast, 11 will have opened in the 1990s and 2000s. Reagan National was the only that opened in the 70s, and Atlanta, O'Hare, Philly, and BWI were the only ones that opened in the 80s.
While it looks like the great airport-downtown rail boom is going to slow down now, these 18 airports account for 310 million boardings annually, or about 45% of all passenger enplanements. Of the 12 without rail, Salt Lake City looks the most promising, and Charlotte's new light rail system runs to the SW, not far from the airport. Some, like Denver and Houston, are too far from their urban cores to reach new light rail systems, while others, like Detroit and Orlando, don't have rail lines to connect to. San Diego and LaGuardia are very close to rail lines, but don't have direct links, although the 992 bus at San Diego gets you downtown much faster than most airport rail links. And LaGuardia was intentionally ignored for rail in order to make Newark and JFK more attractive for travelers heading into Manhattan.
The remaining four with no rail link are Tampa, Cincinnati, Honolulu, and Las Vegas. Cincinnati has no rail and a massive, underutilized airport 12 miles away in Kentucky. Tampa and Honolulu debating whether to start light rail, and the cabbies in Las Vegas have prevented the Monorail from stretching another mile south of the MGM Grand to reach the airport. So it is unlikely we'll get past 20 airports by the end of the next decade.
The economics of bringing rail to all these airports has largely been driven by the fact that people fly a lot more. In 1978, when airlines were deregulated and only Boston and Washington National had rail lines, 290 million passengers boarded planes at U.S. airports. That figure has grown steadily since, to 690 million in 2006. Without this more than doubling of enplanements, it would have been much harder to justify the cost of the rail link, and many lines, including the new Dulles and Sea-Tac connections, have been developed with the primary purpose of reaching the airport. Therefore, the environmentally unfriendly transport of air travel has helped create demand for environmentally friendly rail lines. Something to consider when looking at future transit-oriented developments that will sit near subway stops and light rail stations.