But neither the Klan nor legally dubious covenants nor flagrantly unconstitutional land grabs were arguably as effective as the automobile and its attendant infrastructure at turning Los Angeles into an intentionally segregated city.

When the 1944 Federal-Aid Highway Act allocated funds for 1,938 miles of freeways in California, planners used the opportunity, with full federal support, to obliterate as much as possible the casual mingling of the races.

Local officials rerouted the elaborate designs of freeway engineers — often at considerable expense — to destroy thousands of homes in racially diverse communities. As detailed by Gilbert Estrada in “If You Build It, They Will Move,” mixed-race Boyle Heights was gutted by freeways. Despite a mandate to avoid parks at all costs, planners put lanes through the middle of Hollenbeck Park while spending millions to reroute around a park in the white suburb of San Dimas. Dozens of Boyle Heights homes were destroyed just to give white suburban shoppers easier freeway access to a Sears department store.

Officials justified these actions as “slum clearance”— intended to upgrade the city’s supposedly crumbling housing stock. But their racially malign intent was obvious, laid bare when officials moved the Santa Monica Freeway so that it ran directly through the stately African American middle class neighborhood of Sugar Hill — anything but a slum — wiping it off the map.

When L.A. communities of color rose up in protest at the destruction of these neighborhoods, they were ignored. White areas like Beverly Hills and South Pasadena, meanwhile, successfully fought off freeways planned through their neighborhoods. As noted by Estrada, only 61% of L.A.’s planned freeway network was built as a consequence. This created immediate traffic bottlenecks in the system, which have lingered to this day.

Much of this freeway construction was in service of a suburban housing boom that was explicitly segregationist.

As freeways enabled L.A.’s car-dependent suburbs to expand outward, they did so under the guidance of federal and local policies explicitly designed to keep those neighborhoods white-only. As historian Richard Rothstein detailed in his book “Color of Law,” developers who secured generous federal financial assistance were barred from building racially integrated housing by the Jim Crow federal lending policies of the day. Of the 125,000 Federal Housing Authority units built in Los Angeles County between 1950 and 1954, less than 3% of those were open to people of color.