Calculations have been made of the exposure of people to highway noise in urban areas of the United States from 1974 through 2000. Roadside noise level contours and the numbers of people exposed were calculated in ten sample cities, using a previously developed noise model, traffic parameters obtained from local authorities, and U.S. Census tract data. National totals and future exposure were projected using census bureau data and projections. Future noise exposure was calculated for several scenarios, including do nothing, existing EPA regulations, and several proposed regulations. Parametric analyses were made of operational regulations versus new vehicle standards, automobile versus truck noise, and high speed versus low speed noise. Conclusions were made as to the efficacy of various approaches and the relative importance of driveline versus tire noise and automobiles versus trucks.