a discontinuity bridged by Parker Avenue in Rodeo, the road approaches the Carquinez Bridge and arrives in Crockett as Pomona Street. An AC Transit Rapid Bus (72R-San Pablo Rapid) runs along San Pablo Avenue from Downtown Oakland to Contra Costa College in San Pablo. The express bus line was put in place after a Metropolitan Transportation Commission study determined that it would be more cost-effective than a previous proposal to install light rail along the route. The Bay Area Rapid Transit system runs its Richmond leg parallel to the route up to the El Cerrito del Norte station. The Alvarado Adobe is located by the San Pablo City Hall on the corner of San Pablo Avenue and Church Lane. SR 123 is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration. History San Pablo Avenue is one of the oldest existing roads in the East Bay. It originated in the Spanish colonial era as the Camino de la Contra Costa ("road of the opposite shore", i.e. opposite from the Presidio of San Francisco and the settlement around the Mission in San Francisco) and was legally a "camino real" ("royal road", i.e., property of the Spanish crown) until Mexico won its independence in 1821. It ran from the Encinal ("Oakland") landings of the Rancho San Antonio northward (actually northwestward) along the bayshore, then eastward just inland of the Carquinez Strait. It was the principal thoroughfare for the scattered ranches throughout this part of the East Bay. The name persisted into the American era, when it was still called the "Contra Costa Road". On July 15, 1852, the Court of Sessions of Contra Costa County ordered the construction of a more direct and somewhat improved road along the same general route between the Rancho San Pablo and Oakland, which consequently became known as "The San Pablo Road". This segment subsequently became today's "San Pablo Avenue". In 1927, this road was designated as part of the Lincoln Highway, the nation's first transcontinental road, upon the opening of the new highway bridge across the Carquinez Strait. Prior to the construction of the Eastshore Highway, San Pablo Avenue was the main north–south route through the northern East Bay, carrying the designation U.S. Route 40 north of University Avenue in Berkeley (US 40 proceeded down to the foot of