The Sinclair Freeway refers to portions of two freeways in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

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• Interstate 680 (California)
  Interstate 680 (California)
  Interstate 680 is a north–south Interstate Highway in Northern California. It curves around the eastern cities of the San Francisco Bay Area from San Jose to Interstate 80 at Cordelia, bypassing cities along the eastern shore of San Francisco Bay such as Oakland and Richmond while serving...
  
   - between US 101 and the Alameda County line
• Interstate 280 (California)
  Interstate 280 (California)
  Interstate 280 is a 57-mile long north–south Interstate Highway in the San Francisco Bay Area of Northern California. It connects San Jose and San Francisco, running along just to the west of the cities of San Francisco Peninsula for most of its route.I-280 from its northern end at King...
  
   - between Interstate 880
  Interstate 880
  Interstate 880 is an Interstate Highway in the San Francisco Bay Area connecting San Jose and Oakland, running parallel to the southeastern shore of San Francisco Bay...
  
   and US 101

The portion of this route from the I-280/US 101 junction to Route 17 is named the "Sinclair Freeway". Joseph P. Sinclair was District Engineer for the District 4 Division of Highways (now Caltrans) from 1952 to 1964. Named by Assembly Concurrent Resolution 104, Chapt. 168 in 1967.