Los Angeles adopted its HPOZ ordinance in 1979; the historic districts now number 35, harboring 21,000 properties. Generally, groups of homes within a neighborhood need to be built during a “period of significance,” such as from 1905-1941, to become HPOZ-worthy. Residents in neighborhoods kick-start the process by rallying neighbors in support of the districts. Once one is approved, the city’s Planning Department and HPOZ boards review proposed alterations to exteriors of homes within their zones.
Source: latimes.com – Los Angeles Times