We examined trends in smoke-free workplace policies among all indoor workers in the United States using the National Cancer Institute's Tobacco Use Supplement to the Census Bureau's Current Population Survey (total n = 270,063). Smoke-free was defined as smoking not permitted in public or common areas or in work areas of a worksite. Nationally, we found that nearly 70% of the US workforce worked under a smoke-free policy in 1999. At the state level, a greater than 30-percentage-point differential existed in the proportion of workers with such policies. Although significant progress has been made to reduce worker exposure to environmental tobacco smoke on the job, we predict further progress may be difficult unless comprehensive regulations to protect all workers are implemented at the national, state, or local level.