The original inhabitants of the area now occupied by the city of La Puente were the Tongva. They lived in a village called Awingna, which linguists translate as "abiding place." The Awingna chief Matheo (who also held sway over several other nearby villages) was baptized at Mission San Gabriel in 1774.
In 1769, the Spanish Portol expedition became the first Europeans to see inland portions of Alta California. On July 30, the party camped on the east side of the San Gabriel River, in today's unincorporated area of Bassett. Father Juan Crespi wrote in his diary that, the next day, they had to build a bridge (Spanish "puente") to cross the miry San Gabriel River.
With the establishment of Mission San Gabriel, the area encompassing Awingna and what is now the city of La Puente became part of Rancho La Puente, established as a mission outpost and ranch. The rancho was visited by the Jedediah Smith party in November 1826, the first Americans to travel overland to California.
Following secularization of the missions in the 1830s, former mission ranchos passed into private ownership. In 1842, John Rowland and William Workman were granted the 48,000-acre (190 km2) Rancho La Puente. In 1884, the area was named Puente (bridge in Spanish; in old Spanish the noun was often feminine, as opposed to modern Spanish el puente).
The area was known for its fruit and walnut groves during the 1930s. The city was even home to the world's largest walnut packing plant. Today, the city is heavily urbanized, but the area still has some historical landmarks from its founding days nearby, for instance, the Workman and Temple Family Homestead Museum in neighboring City of Industry.
Redevelopment of the business districts in La Puente have been ongoing. However, the local government has been relatively unsuccessful in its attempts to attract big-box retailers and restaurant chains. La Puente retains many aging 1950s-era strip malls.
As of the census of 2000, there are 41,063 people, 9,461 households, and 8,183 families residing in the city. The population density is 4,542.8/km (11,757.3/mi). There are 9,660 housing units at an average density of 1,068.7/km (2,765.9/mi). The racial makeup of the city is 39.11% White, 1.96% African American, 1.28% Native American, 7.16% Asian, 0.17% Pacific Islander, 45.14% from other races, and 5.19% from two or more races. 83.10% of the population are Hispanic or Latino of any race.
There are 9,461 households out of which 50.0% have children under the age of 18 living with them, 60.4% are married couples living together, 17.9% have a female householder with no husband present, and 13.5% are non-families. 10.1% of all households are made up of individuals and 4.4% have someone living alone who is 65 years of age or older. The average household size is 4.34 and the average family size is 4.48.
In the city, the population is spread out with 33.8% under the age of 18, 11.6% from 18 to 24, 31.0% from 25 to 44, 15.9% from 45 to 64, and 7.7% who are 65 years of age or older. The median age is 28 years. For every 100 females there are 100.1 males. For every 100 females age 18 and over, there are 98.8 males.
The median income for a household in the city is $41,222, and the median income for a family is $41,079. Males have a median income of $26,381 versus $22,018 for females. The per capita income for the city is $11,336. 18.9% of the population and 16.3% of families are below the poverty line. Out of the total people living in poverty, 24.6% are under the age of 18 and 9.3% are 65 or older.