Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259 as of the 2020 census. Santa Clara County and neighboring San Benito County form the San Jose–Sunnyvale–Santa Clara metropolitan statistical area, which is part of the larger San Jose–San Francisco–Oakland combined statistical area. Santa Clara is the most populous county in the San Francisco Bay Area and in Northern California.

The 2020 United States census was the 24th decennial United States census. Census Day, the reference day used for the census, was April 1, 2020. Other than a pilot study during the 2000 census, this was the first U.S. census to offer options to respond online or by phone, in addition to the paper response form used for previous censuses.