San Mateo County is located in the San Francisco Bay Area of California. It covers most of the San Francisco Peninsula just south of San Francisco, and north of Santa Clara County. San Francisco International Airport is located at the northern end of the county, and Silicon Valley begins at the southern end. As of 2005 the population was 712,462. The county seat is Redwood City. It is among the 20 most affluent counties in the United States, in terms of personal, per capita and household income.
San Mateo County was formed from parts of San Francisco County and Santa Cruz County in 1856.
The county bears the Spanish name for Saint Matthew. As a place name, San Mateo appears as early as 1776 and several local geographic features were also designated San Mateo on early maps including variously: a settlement, an arroyo, a headland jutting into the Pacific (Point Montara), and a large land holding (Rancho San Mateo). Until about 1850, the name appeared as San Matheo.

Fairgrounds: https://www.sanmateocountyfair.com

County Website: http://www.co.sanmateo.ca.us/portal/site/SMC

School District: http://www.smcoe.k12.ca.us