Midpeninsula Regional Open Space District

The Midpeninsula Regional Open Space District (Midpen) is an independent special district in the San Francisco Bay Area. Formed in 1972 by voter initiative Measure R, it has acquired, preserved and restored a regional green belt of open space land and provides opportunities for ecologically-sensitive public enjoyment and education.

The district, which includes parts of Santa Clara, San Mateo and Santa Cruz counties, works to form a continuous green belt of permanently preserved open space by linking its lands with other public park lands. A member of the Bay Area Open Space Council, the district also participates in cooperative efforts such as the San Francisco Bay Trail, Bay Area Ridge Trail, and Skyline-to-the-Sea Trail, which are regional trail systems in the Bay Area that include district lands.

The Midpeninsula Regional Open Space District has permanently preserved more than 70,000 acres (28,000 ha) of foothills, baylands, redwood forests, coastal grasslands, oak savannah and other open space across 26 open space preserves. Of the district's 26 preserves, 24 are open to the public free of charge, 365 days a year from dawn until one-half hour after sunset.

The district's tax and voter base consists of about 550 square miles (1,400 km2) and 763,000 people, mostly in Santa Clara and San Mateo counties. District revenues for fiscal year 2025-2026 were projected to be $94.4 million, with $82 million coming directly from a portion of property taxes. The district also occasionally receives state and federal grants, as well as private donations and rental income.

The District's stated mission is:

To acquire and preserve a regional greenbelt of open space land in perpetuity; protect and restore the natural environment; and provide opportunities for ecologically sensitive public enjoyment and education.

On the Coast, Midpen has an expanded mission:

To acquire and preserve in perpetuity open space and agricultural land of regional significance, protect and restore the natural environment, preserve rural character, encourage viable agricultural use of land resources, and provide opportunities for ecologically sensitive public enjoyment and education.