The Monterey Branch was built in 1879 and opened to traffic on January 1, 1880; it linked San Francisco to the Hotel Del Monte and Pebble Beach. It branched from the Southern Pacific Coast Line main line from a wye at Castroville, just north of Salinas. It extended generally south and west, and served the (now closed) US Army's Fort Ord, the canneries and packing houses of Monterey and Seaside, and a lumber yard in Pacific Grove.

The line hosted SP's longest running "named" passenger train, the Del Monte, which ran from San Francisco to Pacific Grove. The train was mainly used by wealthy tourists. The Del Monte made its last run on April 30, 1971, at the dawn of Amtrak. Amtrak could not legally operate the train because its route was 125 miles long, not 150 as Amtrak required. SP however, maintained that it was a long distance train and thus the operations ceased.

As the line began to fall into disuse, starting in the 1980s and into the 1990s, operations along the track were cut back in sections over time. By the latter part of 1980s, the condition of the track had deteriorated considerably; today the track remains, but is buried underneath the bike trail.

The last train that ran on the line was in 1999 when TAMC (Transportation Agency of Monterey County) ran a Talgo trainset on the line for demonstration purposes. However, the demonstrations were canceled due to the poor condition of the track. While the tracks are still in place into the town of Monterey, the line has not been used since 1999, when Union Pacific removed the switch at the junction with the Coast Line at Castroville in November of that year.

TAMC purchased the line from Union Pacific in 2003 and commuter rail to be operated by Caltrain has been proposed numerous times. However, the residents of the upscale communities along the tracks as well as the cities themselves have not been supportive.

The western end of the right of way is generally scenic, with a tree-lined walking path in one area, and a paved bike/walking path where the route ran along the southern boundary of Monterey Bay. Further north/east, the line runs through coastal dunes, parallel to California Highway 1. The route crossed over the Salinas River on a large truss bridge.