A number of factors, including the end of World War II, the G.I. bill, and the advent of the affordable family automobile, led to the rapid expansion of the American suburbs. Between 1945 and 1946, the number of new housing starts more than tripled, increasing from 326,000 to 1.02 million in just one year. The total value of construction grew accordingly, from $6.7 billion to $25.4 billion, adjusting for inflation.
The Levittown house was a popular model for a suburban home. At just 750 square feet, the homes were relatively inexpensive and ready for mass production. In 1950, the year Time magazine estimated that Levitt and Sons built one out of every eight houses in the United States, the average size of a newly built single-family home was 983 square feet — slightly smaller than a decade prior, when it was 1,177 square feet.
The 20th century was a period of economic growth and prosperity for the American consumer, as was the 21st century in the most part. With inflation-adjusted GDP per capita increasing from $10,164 in 1920 to $51,646 in 2016, Americans today are as wealthy as they’ve ever been. Home sizes have also increased, keeping pace with consumer demand. The average single-family home built today is 2,657 square feet — more than twice the average single-family home built in 1920.
Just 9.2% of the population lived in the suburbs in 1920. By 1950, that figure had more than doubled to 23.3%, and by 2000, half of all Americans lived in the suburbs. One of the largest 10-year growth periods in home size occurred between 1953 to 1963. During that decade alone, the average size of a new single-family home grew by nearly 60%.
Americans actually have more room than their rising home sizes suggests because as home sizes grew, the average number of occupants in a household has declined steadily — from 4.34 people in 1920 to 2.54 people today, a historical low. So while the size of an average home has more than doubled since 1920, the average square footage per person has more than quadrupled.
One major reason for the falling number of people in a household is the changing composition of the American family. Marriage rates are low, and many more children are growing up in one-parent households than ever before. The share of one-parent families with children under the age of 18 has grown from 7.4% of all families with children in 1950 to 31.3% in 2015. Similarly, more adults are living alone than ever before. The single-person occupancy rate increased from 7.7% in 1940 to 26.7% in 2010.
To determine the average size of a newly constructed single-family home between 1971 and 2016, 24/7 Wall St. used survey data from the Census Bureau’s American Housing Survey. For the years 1963 and 1970 we used data from the Census Bureau’s U.S. Department of Housing and Urban Development’s 1969 “Characteristics of New One-Family Homes” construction report. For the years 1940, 1950, and 1954 to 1956, we used the Bureau of Labor Statistics New Housing and its Materials 1940-56 report. For all other years, we estimated the average size of a newly constructed home using construction data on residential housing starts and total residential floor space constructed in a given year from the Census Bureau’s annual “Statistical Abstracts of the United States” and its “Historical Statistics of the United States, Colonial Times to 1970” report. We took the quotient of total residential floor space and total residential housing starts and made adjustments to account for the inclusion of multi-family housing units and exclusion of various states in the national tally of total floor space constructed. We also adjusted housing starts to better approximate housing completions. Average household size also came from the Census Bureau. GDP per capita figures for years 1929 to 2016 are from the Bureau of Economic Analysis. GDP per capita figures for years 1920 to 1928, which were not available from the BEA, came from estimates by the Maddison Project.