This brief is the seventh in a series of briefs that constitute a body of knowledge describingcommuting in America. This body of work, sponsored by AASHTO and carried out in conjunctionwith a National Cooperative Highway Research Program (NCHRP) project thatprovided supporting data, builds on three prior documents covering this topic that wereissued over the past three decades. Unlike the prior reports that were single volumes, thiseffort consists of a series of briefs, each of which addresses a critical aspect of commutingin America. These briefs, taken together, comprise a comprehensive summary of Americancommuting. The briefs are disseminated through the AASHTO website. Accompanyingdata tables and an Executive Summary complete the body of information known as Commutingin America 2013 (CIA 2013).