America's transportation system continues to change along with the population, work force, and economy. The following table puts those changes in perspective:

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Context 1990 2007
Resident population (thousand) 248,791 301,621
Total area (thousand sq. mi.) 3,718 3,794 (2000) a
Total civilian labor force (thousand) 125,840 153,124
Real gross domestic productb (trillion) $7.1 $11.5
Median household incomeb,c $36,668 $41,924
Average household incomeb,c $39,073 $51,929 (2006)
Average household expendituresb,c $35,257 $42,204 (2006)
Number of households (thousand) 93,347 116,011
Life expectancy at birth (years) 75.4 77.8 (2005)

a Data for 2000 include inland water, coastal water, Great Lakes, and territorial water. The Census Bureau tabulates area data for the decennial census years only.

b Data in 2000 chained dollars (see Glossary for definition).

c BTS computations, November 2007 and October 2008.

Sources: Area - U.S. Department of Commerce (USDOC), U.S. Census Bureau, Statistical Abstract of the United States: 2002 and 2008, available at as of October 2008. GDP - ;USDOC, Bureau of Economic Analysis, available at as of October 2008. Population, number of households, and median household income - USDOC, Census, available at as of October 2008. Average household income and expenditures, and labor force - U.S. Department of Labor, Bureau of Labor Statistics, available at as of October 2007. Life expectancy - Centers for Disease Control and Prevention, available at as of October 2008.