To measure the full scope of transportation services and their contribution to the economy, BTS and BEA jointly developed the Transportation Satellite Accounts (TSA). The TSA measure the contribution of both for-hire and in-house transportation to the economy, totaling about $370 billion in 1997, accounting for 4.4 percent of the gross domestic product.

The TSA also estimate the value added by different modes of transportation (figure 6-1), facilitating analysis of trends and comparative assessments across modes. In both for-hire and in-house transportation, truck transportation services contributed the most to U.S. Gross Domestic Product: $81.4 billion and $116.7 billion, respectively. BTS will explore the possibility of enhancing future versions of the TSA to capture the economic contribution of personal transportation and other transportation services, such as the in-house use of automobiles.