National Public Lands Day © Stephen Matera/Tandem Stills + Motion
National Public Lands Day takes place every fourth Saturday of September. Today is all about preserving public lands, which can be anything from national parks to urban green spaces. On this day, entry fees to many federal lands are waived, and those who participate in conservation activities like cleanups or restoring historic structures receive free entry coupons for future visits to these locations. This day has grown substantially since it began in 1994. Its first celebration was started by three national agencies and drew 700 volunteers. By 2010, the number of volunteers had increased to 170,000, spreading across more than 2,000 sites.