Rancho La Puente was a ranch in the southern San Gabriel Valley that measured just under 49,000 acres (200 km2), and remained intact from its establishment in the late 1700s as an outpost of Mission San Gabriel until about 1870. By modern landmarks, the ranch extended from San Gabriel River on the west to just west of the 57 Freeway on the east and from Ramona Boulevard/San Bernardino Road on the north to the Puente Hills on the south. All but 40 acres (160,000 m2), which fall within Orange County, are within Los Angeles County. Today, the present communities of Avocado Heights, Bassett, Baldwin Park, San Dimas, Rowland Heights, Hacienda Heights, City of Industry, La Puente, Walnut, Covina, West Covina, and small sections of South El Monte and Irwindale are contained within the old boundaries of Rancho La Puente.
The name "La Puente" originates from the Spanish Portola Expedition of 1769-1770, the first land-based exploration of Alta California by Europeans. In July, 1769 the party came north through "la abra" (corrupted later into La Habra), "an opening" or pass through the Puente Hills. Descending down into a valley the expedition dubbed "San Miguel" (now the San Gabriel Valley), the group headed northwest and camped near a large stream (now the San Gabriel River). Father Juan Crespi noted in his diary that the expedition had to build a bridge ("la puente") to cross the stream because the channel was so miry. That first bridge, and later more permanent bridges across the river, gave the area its name.