According to information provided by the National Ski Areas Association, there were 45 fewer ski areas in operation during the 2018/19 season then there were just 20 years ago. The National Ski Areas Association (NSAA) reports 476 ski areas were in operation during the 2018/19 season down from 521 operating ski areas during the 1997/98 ski season.
This information is based on info gathered for the Kottke National End of Season Survey. Each season several areas are unable to open due to weather. The change in the number of operating areas is often because several areas close during a season and reopen for the following season. However, many of the 45 ski areas are now fully defuncted and unlikely to ever open again.