In the past three-four decades urban sprawl has led to the rapid expansion of low density development across once pastoral landscapes, vastly increasing the area now occupied by the built environment. While, as urban planners, we are almost universally opposed to wanton sprawl, there are a few beneficiaries from sprawl beyond just builders and developers. One of these beneficiaries is satellite airports in communities which are reasonably proximate to larger population centers that see increased air traffic and passenger growth due to their airport being closer geographically to suburbs and exurbs of the larger population center.Seasonal air service from carriers like Allegiant and Sun Country have contributed to much of the growth, as have low(er) cost carriers such as AirTran, JetBlue, and Southwest.

Here are some examples with rounded 2011 passenger (pr “pax”) totals (all passenger data are from en.wikipedia.org for each airport facility, except where noted):

Two examples from the Great Lakes Region show Greater Chicago-Rockford International has seen a re-emergence of air traffic in the past few years, increasing from zero passengers in the 2001-2003 time frame to more than 183,000 passengers in 2011. Bishop International Airport in Flint, Michigan is regularly hovering around one million passengers a year and is now the third busiest airport in the state behind Detroit Metropolitan and Grand Rapids’ Gerald Ford International. Meanwhile, Stewart International Airport north of New York City saw 414,000 passengers in 2011 and MacArthur Airport on Long Island is now serving over 850,000 passengers a year.

In some instances, even major airports can benefit from the city’s proximity to another major city and its ring of suburbs. BWI (Baltimore-Washington International) is an excellent example of this occurrence due to its convenience to our nation’s capital.

Does this mean that satellite airports are flying “sky-high” indefinitely? Not in all cases. Ontario International Airport east of Los Angeles has seen a significant decline in passengers in the past five years. Exact reasons why are not clear, though the gain (or loss) of a major carrier, particularly a discount one can have a big impact on the numbers. The economic downturn starting in 2008 may also be a factor. In the cases of Manchester-Boston Regional Airport and Providence’s T.F. Green Airport. they both were specifically designated by New England transportation planning officials to serve as alternatives to the northern and southern suburbs of Greater Boston instead of constructing an entirely new regional airport. Both saw enormous passenger growth during Boston’s “Big Dig” project. While passenger traffic is down from their peak, Manchester-Boston served more than 2.7 million passengers in 2011 and T.F. Green served nearly four million passengers that year.

The trend in satellite airport growth documented above is not solely an American phenomenon. Two prominent examples come from the United Kingdom. Luton (9.5 million passengers in 2011) and Stansted (18.0 million passengers in 2011) airports located northwest and northeast of London, England have also seen dramatic growth in recent decades. Both supplement massive amount of air traffic using Heathrow and Gatwick airports (over 100 million passengers combined). They each rank fifth and forth respectively in the United Kingdom.

In most cases, the growth in passengers and air traffic at satellite airports appears to be a result of the suburban sprawl steadily moving closer to the airport facility. This makes the airport a more attractive alternative to those individuals and businesses that have located within reasonable travel proximity to the satellite airport. From a planning perspective, there are both pluses and minuses regarding the trend.

Yes, the dispersal of air traffic helps reduce both air traffic and ground transportation congestion in those major cities and many result in some shorter automobile trips to the airport. In addition, the more effective use and/or reuse of our existing airport infrastructure is preferable to constructing new airports on greenfield sites. But, the sprawl that induced the growth at these satellite airports still retains many of the negative side effects of low density sprawl development. As a result, the “success” of satellite airports does have corresponding downsides, though they are not necessarily ones that are directly caused by the airports themselves. Instead, the growth at satellite airports can perhaps be considered the silver lining rather than the cloud.