In 1950 40% of people were living in the suburbs. Now 55% are[0]. And that's against a population growth from ~148M then to ~330M now, so 59M suburban people then compared to 180M now and corresponding pressure that would make on size of car parks, moving shops out of centers to places they can have larger car parks, combined with more households with car ownership since 1950 and more cars per household. More population needing more housing, houses trending larger suggests they are more likely suburban or rural than city center, meaning larger overall suburbs and therefore further to travel to get anywhere.
Pew Research[2] says suburbs have grown 6.4 million people by migration from cities and rural populations between 2000 and 2018. Ten fastest growing communities in America in 2021 are suburbs[5].
Car companies made and sold about 58 million cars in the USA in the 1950s decade[3].
Eisenhower's interstate highway act was 1956, and miles of highway has increased by hundreds of thousands since 1990[4].
[0] https://www.insider.com/vintage-photos-levittown-suburbs-50s... and https://www.pewresearch.org/social-trends/2018/05/22/demogra...
[1] https://transportgeography.org/contents/chapter8/urban-trans...
[2] https://www.pewresearch.org/fact-tank/2018/10/02/5-facts-abo...
[3] https://en.wikipedia.org/wiki/American_automobile_industry_i...
[4] https://www.statista.com/statistics/183397/united-states-hig...
[5] https://legallysociable.com/2021/09/19/the-ten-fastest-growi...