The Iron Horse Regional Trail is a multi-use, whole-access trail between Concord and Pleasanton that follows the Southern Pacific Railroad right-of-way established in 1891 and abandoned in 1978. Begun in 1986, it runs 34.3 miles from Concord to Livermore and, when completed, will span over 50 miles from the Alameda County / San Joaquin County line to Suisun Bay in Contra Costa County, connecting two counties and nine communities. The trail corridor links residential and commercial areas, business parks, schools, public transportation, open space and parks, regional trails, and community facilities, and it continues to grow with planned extensions east through Livermore and northward to Martinez. Connected to it is the Tassajara Creek Regional Trail and Tassajara Creek/Ridge Trail, a multi-use hiking, bicycling, and equestrian route extending from the lowlands of Tassajara Creek in Alameda County to the ridgeline above Dougherty Valley in Contra Costa County. This unpaved and paved trail runs north from the Tassajara Ridge Trail Staging Area at Windemere Parkway to Camino Tassajara in San Ramon, with roughly 4.4 miles of existing paved segments in Alameda County connecting from the Iron Horse Trail in Dublin along Tassajara Creek to the Contra Costa County line. Gaps still prevent continuous travel between the two counties, but when completed this trail will extend 9.9 miles from the Iron Horse Trail to Mount Diablo State Park.