The school currently serves northern Ontario and southern Rancho Cucamonga.

In 1911, enrollment was opened to students from Upland and the school was renamed in honor of the Chaffey brothers.

Almost all the high school-age students in western San Bernardino County attended Chaffey, a trend that continued until the 1950s.

The school's buildings were rebuilt and many new ones were constructed during the government public works programs of the New Deal.

Chaffey College continued to operate on the campus until 1960, when it was relocated to the nearby community of Alta Loma.