Residents of Mercer and the surrounding communities gathered yesterday to celebrate the 41st annual Loon Day. About 250 vendors, local organizations and clubs set up tables along Lakeview Avenue and Railroad Street. The streets were closed to motor vehicles to make room for foot traffic. Vendors came from as far as Iowa and Florida, and have been doing so for years, wrapping their vacation time around the celebration. Organizers say they expected at least 10,000 visitors, but with crowds arriving early, attendance numbers may be higher than that.