The Whittier Narrows is a water gap between the Puente Hills to the east and the Montebello Hills to the west. The gap is located at the southern boundary of the San Gabriel Valley, through which the Rio Hondo and the San Gabriel River flow through to enter the Los Angeles Basin. The gap is also traversed by both Interstate 605 and California State Route 19.HistoryThe first European land exploration of Alta California, the Spanish Portolà expedition, discovered Whittier Narrows on its return journey to San Diego. On the outbound journey, the party had followed San Jose Creek, reaching the San Gabriel River north of the Narrows. Franciscan missionary Juan Crespi noted in his diary, "We started out in the morning through the gap of the valley of San Miguel, which is very full of trees. We traveled a long while to the southwest on the edge of the stream, which, rising from a copious spring of water in the same gap, merits now the name of river; its plain is covered with willows and some slender cotton woods."Whittier Narrows was the meeting point for boundary corners of several land-grant ranchos, created during the Spanish-Mexican era, including the Rancho Paso de Bartolo.
