Urban decay is a result of a combination of factors including poverty, poor urban planning, obsolete infrastructure, population shifts, racial discrimination, immigration restrictions, suburbanization and neighborhood redlining. It is characterized by qualities such as the presence of abandoned buildings, high crime rates, diminishing political influence, fragmented families, depopulation, high unemployment, desolate city landscapes and deindustrialization.
Urban decline can also lead to urban decay. In cases such as redlining, this kind of discrimination forces the discriminated to move to friendlier cities, where such a practice is not extreme or is nonexistent.
Poor planning of land use can force people to migrate to other cities, especially if a city lacks adequate or affordable housing. Poor infrastructure and transportation discourage potential investors and force existing businesses to move elsewhere.
Economic decline can give rise to extreme poverty, which contributes to high levels of crime and drug abuse. People always move to areas where they feel safe, especially those with families. People also move for economic reasons. If a city is not doing well economically, it is likely to suffer a population decline if the situation worsens.
Urban decay became prominent in Europe and North America by the late 20th century. Decades later, urban decay spread throughout the world, owing to major changes in global economics, government policy and transportation.