Ancient artifacts discovered by archaeologists suggest that what is now the city of Rialto was settled prior to 1500. Such artifacts, now found at the Rialto Historical Society, indicate that the Serrano Indians lived in the Rialto area between 1500 and 1800 AD. There is no indication as to where these Indians went or why.
In 1842, the Lugo family was granted the Rancho San Bernardino-a holding of 37,700 acres-which encompassed Rialto. In 1851, the Mountain Family purchased part of the Lugo family’s Rancho San Bernardino, and claimed several other portions of the bench which later became known as Rialto. This claim was later amended by the United States Government, permitting them a smaller fraction of the initial purchase.
An adobe building from the early 19th century which was used for many purposes over the years, is the oldest building still standing in Rialto and stands restored in Bud Bender Park, formerly known as “Lilac Park”. The City of Rialto leases the house and a small portion of park land to the Rialto Historical Society for $1 annually.
In 1887 a railroad connector line was built between San Bernardino and Pasadena by the Santa Fe Railroad. Along the line, townsites were located every 2,600 yards (2,400 m) and by the fall of that year over 25 new towns were being built. This same year the Semitropic Land and Water Companywas formed to organize the purchase and selling of real estate, water, and water rights and privileges.
In the fall of 1888, the first school was built and Brooke School District was formed. Records show that up until 1920, the Brooke School District was in continuous operation, except for a very short time in 1888. The prominent Rialto Trapp family bought the first school house in 1921, remodeled the building, and members of the family resided in it until it was destroyed by fire. The Rialto School District (today Rialto Unified School District), was formed in 1891. The staff consisted of two teachers and a principal with separate play areas for the boys and girls.
The Chamber of Commerce was established in 1907. The Chamber incorporated in the spring of 1911. By 1911 the population had grown to 1,500 with 40 businesses and a local newspaper. The election results on October 31 of the same year were 135 for the incorporation of the city and 72 against.
Foothill Boulevard was repaired in 1913 and became U.S. Route 66 a section of the US highway system. In 1914 Los Angeles’ Pacific Electric Railway completed its San Bernardino Line through the City of Rialto, with a junction at Riverside Avenue for the Riverside Line. Today the Tracks above First Street are a part of theUnion Pacific and the Pacific Electric depot on Riverside Avenue is Cuca’s Restaurant.
A fire in the 1920s swept through and destroyed many of the buildings in the downtown area.
Rialto’s population growth had increased to 3,156 by 1950. In 1956 the population soared to 15,359. By 1964 it showed increase to 23,290 and 33,500 in 1978. Rialto is 4 miles (6.4 km) wide and 8.5 miles (13.7 km) long. Rialto’s population grew from 80,000 in 1994 to over 91,873 in 2000.