The count should be done at the employer level (firm- or corporate-wide), not the individual location level. Therefore, for a single corporate entity with multiple locations, all employees at all locations are counted. For example, if a single corporation has 50 small locations (e.g., kiosks, concession stands) with at least 100 total employees in its combined locations, that employer would be covered even if some of the locations have no more than one or two employees assigned to work there.