The Los Angeles Basin contains one of the highest concentrations of crude oil in the world, with over five thousand active oil wells in Los Angeles County.¹ Oil development in this region began in the 1890s and reached its peak in the 1930s, making up nearly half of California’s oil production at the time and nearly one-quarter of the world’s oil output.² Urban and suburban development grew alongside active oil production. Oil development is both ubiquitous and invisible in the city of Los Angeles, which has the largest urban oil field in the country and over one thousand oil wells.