America's transportation system has changed along with the nation's society and economy. The following table puts those changes in perspective:

Excel | CSV

Characteristic 1970 2000
Resident population (thousands)       203,984      281,422
Total area (thousands of square miles)a         3,619  3,718 (1990)
Total civilian labor force (thousands)        82,771       140,863
Real gross domestic productb $3.4 trillion $9.2 trillion
Median household incomeb       $29,600       $39,200
Average household expendituresb N       $35,384
Number of households (thousands)         63,401       104,705
Average life expectancy (years)             71   76.7 (1998)
Labor force participation by women            46%          60%

a 1990 data include the Great Lakes and inland and coastal water. Estimate for 2000 not yet available. 1970 data include inland water only. The Census Bureau tabulates area data for the decennial census years only.

b Expressed in 1996 chained dollars (see Glossary for definition).

Key: N = data do not exist. Note: All dollar amounts are 1996 chained dollars.

Sources: Population, area, number of households-U.S. Department of Commerce (USDOC), Census Bureau, Statistical Abstract of United States: 2000, available at; GDP-USDOC, BEA; median household income-USDOC, Census Bureau, available at; expenditures, employment-U.S. Department of Labor, BLS; life expectancy-Centers for Disease Control and Prevention, available at