The following information about Pacheco was derived from Wikipedia:

Pacheco is located 5.5 miles (9 km) north of Walnut Creek, has a total area of 0.7 square miles
of land and  a population of approximately 3,800.

History

The town was laid out in 1857 by Dr. J.H. Carothers and named for Salvio Pacheco, grantee
of the Rancho Monte del Diablo Mexican land grant. A post office operated at Pacheco
from 1859 to 1913 and from 1955 to the present.

Pacheco was briefly a prosperous commercial center. During this period, Pacheco Slough was
deep enough to receive ocean-based shipping. A series of fires and floods, as well as an
earthquake, destroyed the town and filled the Slough with silt during the 1860s.
Pacheco was subsequently depopulated by the attraction of the nearby town
of Todos Santos, later to be known as Concord.