Earnings of workers in the construction industry vary by the education and experience of the worker, type of work, the size and nature of the construction project, geographic location, and economic conditions. Earnings of construction trade workers are often affected by poor weather. Heavy rain may slow or even stop work on a construction project. Traditionally, winter is the slack period for construction activity, especially in colder parts of the country, but there is a trend toward more year-round construction even in colder areas. Because construction trades are dependent on one another—especially on large projects—work delays in one trade delay or stop work in another. Earnings in selected occupations in construction in 2002 appear in table 5.
 

About 19 percent of construction trades workers were union members or covered by union contracts, compared with about 15 percent of workers throughout private industry. Many different unions represent the various construction trades and form joint apprenticeship committees with local employers to supervise apprenticeship programs.