Why did people flee the inner cities?

Why did huge numbers of people in the USA move to the suburbs after WWII?  During the 1920s and early 1930s people either lived in rural areas or in the center city.  Most of today’s suburbs were farmland during the 1940s.  Suddenly after WWII, suburbs began a dramatic growth.  The surge was so explosive that when the USA did the 1950 census it began classifying urban people a new way.  Each person was classified as living either inside the central city or outside the central city.  In 1950 the breakdown was 60% living in the central city and 40% living in the suburbs.  By 1980 the percentages reversed with 40% living in the central city and 60% living in the suburbs.

Understanding why people began moving to the suburbs is important.  The migration had a huge impact on U.S. energy use (suburban living encourages driving; urban living encourages walking) and schooling (suburban schools are often superior to urban schools).  Understanding the movement also helps answer if governments should try to rebuild or simply raze problematic inner cities like Detroit or Buffalo.

I have heard numerous reasons why the suburbs suddenly became attractive, but none made complete sense to me.  The two most prominent reasons were about highways and safety.  Highways made travel to and from the suburbs easier.  The problem with focusing on highways is that the Federal Highway system was created in 1956.  This is roughly a decade after the movement to the suburbs began in earnest.  Another idea I have heard was that the suburbs were safer than the cities.  Crime, as measured by people in jail, increased during the Great Depression but peaked in 1939.  After 1939, however, the number of people in jail decreased for about five years and then was stable until the 1960s.  These facts suggest rising crime rates were not pushing people out of cities since the USA began to get safer as jobs became more plentiful after the Great Depression.

The answer that I just found is in a book called “The Making of the Atomic Bomb” by Richard Rhodes.  This book is very long and quite detailed.  Chapter 19 relates what happened after the first atomic bomb, nicknamed Little Boy, was dropped on Hiroshima’s city center on August 6, 1945.  The chapter contains the below graph, which shows the chance of death compared to the distance from the bomb’s epicenter.  People very close to the bomb had a 100% chance of dying.  Being 1 kilometer from the bomb meant a 50% chance of dying.  Being 2 kilometers away lowered the chance to 15%.  People 4 kilometers away survived the blast.

After the war one of the fathers of the bomb Edward “Teller thought that civil defense measures such as the dispersal of cities might prove effective against atomic bombs” (pg. 757).  The move to the suburbs was an issue of safety, but not from muggings and burglaries.  Instead, at the end of World War II people and the government sought to minimize their own chances of extermination during the global nuclear arms race by living away from center cities and spending only their working hours exposed to the downtown danger zone.

Today’s nuclear bombs are orders of magnitude larger than the 12.5 kiloton bomb dropped on Aioi Bridge in Hiroshima.  As bomb yields have gotten larger, living in the suburbs has offered people less protection in the event of a catastrophic war.  This combined with a falling threat of US cities being “nuked” has resulted in a return of people wanting to live in the central city.

Because of the large increase in the US’s population since WWII, I don’t think the suburbs are ever going away.  Nevertheless, the break-up of the USSR in the late 1980s, which reduced the chance of nuclear disaster, had an interesting and unexpected result; the revival of center city living in the US.  The cause of the suburban migration was a desire for safety; from the bomb, not from crime.