Figure 3. Transportation Employment by Mode (thousands), January 1990 - July 2010
Source: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, http://www.bts.gov/publications/key_transportation_indicators/
Figure 3 shows the trends and seasonality in transportation employment by mode from January 1990 through July 2010. Both truck and transit employment appear to exhibit the greatest seasonal variation, as exemplified by the cyclical movement in these two series over time.