Two major regional bottlenecks, the Springfield Interchange and Woodrow Wilson Bridge, were massively reconstructed with completion in 2007 and 2008. Generally, Potomac River crossings remain major choke points; proposals to add crossings (such as near Leesburg or Quantico as part of a long-proposed Outer Beltway) are opposed by Virginia communities near the suggested bridge sites, and by Marylanders who fear that new bridges would bring new housing development to green space in that state such as Poolesville. Because of Northern Virginia's high housing costs, tens of thousands of employees there choose more affordable housing far away in outer Virginia exurban counties, or in Prince George's County and Southern Maryland, thus creating tremendous traffic congestion on the Potomac bridges. This situation is much like metropolitan areas of California. Furthermore, Fairfax County localities such as Great Falls, Dranesville, and Clifton impose low-density, large-acreage residential zoning, which forces developers to leapfrog into Loudoun and Prince William counties to build housing, thus increasing commuters' driving distances. In recent years, developers have continued to develop in Loudoun County but have filled Prince William County. Therefore, many developers have been moving south to Stafford County where local government has been more reluctant to developments.