In the 1800s and first half of the 1900s, as the Bay Area grew, industrial and commercial activities proliferated along the shoreline of San Francisco Bay. By the 1950s, 85 percent of the Bay’s wetlands had been filled in, dried out or converted to salt ponds, and an astounding four square miles of Bay were being filled each year. In 1965, responding to citizens’ demands for protection of the Bay’s natural environment, the state legislature passed the McAteer-Petris Act, which established the San Francisco Bay Conservation and Development Commission (BCDC) and charged it with preparing a plan for the long-term use and protection of the Bay and with regulating development in and around it. BCDC now requires that maximum feasible public access be provided as part of any project that proposes to alter the shoreline.

At the time of the Commission’s creation, only four miles of the Bay’s shoreline was accessible to the public. Since then, that figure has grown steadily thanks not only to BCDC’s efforts but also to initiative by cities, counties, and State and Federal agencies to protect and restore the Bay and to create new recreational opportunities. In 1987, then-state Senator Bill Lockyer (now the state’s Attorney General) conceived of a plan for a so-called "Ring around the Bay," a hiking and bicycling trail that would encircle San Francisco and San Pablo bays. He authored Senate Bill 100 (SB 100) authorizing the Association of Bay Area Governments (ABAG) to "develop and adopt a plan … for a continuous recreational corridor which will extend around the perimeter of San Francisco and San Pablo bays."

SB 100 required that the plan include a specific trail route; the relationship of the route to parks and other recreational facilities; links to existing and proposed public transportation facilities; an implementation and funding program for the trail; and provisions for implementing the trail without adversely affecting the natural environment of the bay. SB 100 was introduced or co-authored by the entire Bay Area legislative delegation and passed into law with widespread support. The Bay Trail Plan was developed over a two-year period by an advisory committee to ABAG that included representatives from a broad range of interests, including Federal, State, regional and local government agencies, environmental and recreational organizations, private landowners and large business corporations. The Plan was adopted by ABAG in July 1989, and its policies and proposed alignment continue to guide the development of the Bay Trail.

The San Francisco Bay Trail Project, a nonprofit organization administered by ABAG, was created in 1990 to plan, promote and advocate implementation of the Bay Trail. By 1999 slightly more than half the Bay Trail’s ultimate alignment—approximately 210 miles—had been developed.