However, the name was evidently well established when Munro-Fraser (1879) wrote his History of Solano County.

[3] The lower (south) summit of Twin Sisters is the site of a pre World War II crash on 24 October 1941 of an Army Air Corps B-18A Bolo bomber that killed all five crew members during a relatively short flight from Hamilton Field military air base to nearby McClellan Field.

The south summit is also the highest privately owned peak in the San Francisco Bay Area, which led in 2003 to the building of a controversial house, the "house above the morning clouds", very close to the summit crash site by Cigarettes Cheaper!

This led to subsequent calls for county ordinances to prevent future ridge-top building.

What little wreckage of the B-18A bomber remains is located only 100 feet (30 m) from the driveway leading to the charred ruins of this house.