emerged in the 1930s, but by the 1980s it had become, said Mayor Young, "a vision from hell." During the height of the drug era, Detroit residents routinely set fire to houses that were known as popular drug-dealing locations, accusing the city's police of being either unwilling or unable to solve the deep problems of the city. The arson primarily took place in the inner city, but surrounding suburbs were often affected as well. The crimes became increasingly destructive throughout this period. Over 800 fires were set, mostly to vacant houses, in the peak year 1984, overwhelming the city's fire department. In later years, the arsons continued, but the frequency of these fires was reduced by razing thousands of abandoned houses, buildings that were, in many cases, used to sell drugs. 5,000 of these buildings were razed in 1989–90 alone. Every year the city mobilizes "Angel's Night", with tens of thousands of volunteers patrolling high-risk areas in the city. Problems Urban decay Detroit has experienced significant urban decay—the process in which a previously flourishing city falls into disuse and disrepair, characterized commonly by empty plots of land, abandoned, decrepit, and often vandalized buildings, high unemployment rates, and high crime rates. Detroit has become one of the most infamous examples of such cities in the United States. Abandoned residential and commercial buildings are very widespread; in 2014, 30% of residential buildings in the city were partially or fully vacant. The problem is so severe that the city has been likened to a ghost town. In the 1940s, Detroit was the fourth-largest city in the US thanks in large part to the automobile industry. Vehicle manufacturers Ford, General Motors, and Chrysler had their factories there, which made the city a source of employment for many people. In the 1950s, the industry was no longer confined to Detroit; it began to spread out when vehicle manufacturers began to move their factories elsewhere, which led to the old factories being closed and abandoned, and eventually many of them were vandalized. This was a side effect of automation and globalization. Detroit now holds the name of "America's comeback city". However, blight remains specifically in predominantly African American neighborhoods. A significant percentage of housing parcels in the city are vacant, with abandoned lots making up more than half of total residential lots in large portions of the city. With at least 70,000 abandoned buildings, 31,000 empty