Wildfire activity is increasing in the western United States at a time when outdoor recreation is growing in popularity. Because peak outdoor recreation and wildfire seasons overlap, fires can disrupt recreation and expose people to poor air quality. We link daily data on campground use at 1069 public campgrounds across the western United States over a ten-year period to daily satellite data on wildfire and smoke. We use this data set to (1) tabulate the number of campers affected by wildfire and smoke at campgrounds across the western US, and (2) provide estimates of how campground use responds to wildfire and smoke impacts, including the first causal estimates of the impacts of wildfire smoke on recreation behavior. We find that, on average, more than 120,000 campground visitor-days per year are close to an actively burning fire and nearly 400,000 are impacted by adverse smoke conditions. In some regions more than 10% of camper-days occur when air quality is poor due to wildfire smoke. Combining the results with monthly national park visitation data at the 30 parks in our sample, we estimate that fire and smoke affect 400,000 and 1 million visitor-days per year, respectively. Using fixed effects panel regressions at the campground level, we estimate declines in campground use in response to fire and smoke. The magnitude of the smoke effect is small, however, suggesting that smoke fails to deter most visitors to public lands. Back-of-the envelope calculations based on our findings and estimates from the literature suggest that most of the total welfare losses accruing to campers due to smoke occurs via health impacts from trips taken in spite of smoky conditions, rather than due to cancelled trips.