The use of zip codes for spatial, demographic, and socio-economic analysis is growing. As of August 2005, 193 articles were indexed by "zip code" in the Social Sciences Citation Index, while 386 were indexed in PubMed. All of these articles were published since 1989. While the treatment of zip...

Essential air service (EAS) is a federally funded program that helps provide commercial air transport service from smaller, geographically remote communities in the United States. While critics of this program frequently cite the underutilization of EAS connections as being an indicator of...