The vast majority of establishments in the industry were fairly small, employing fewer than 5 workers. Self-employed individuals operated many of these small firms. Despite the prevalence of small firms and self-employed workers, large firms tend to dominate the industry. Approximately 35.3 percent of jobs are found in only about 1.4 percent of the establishments, and some of the largest firms in the industry employ several thousand people.

Although employees in this industry work in all parts of the country, many workers are concentrated near large urban centers.