They had this weird thing called home mortgages even back then
As well as GI Loans, which fueled the housing boom and large scale developments such as Levittown.
The houses were small by today's standards. In Washington DC, a newly constructed 2 story brick and block attached house with a full basement could be had for just under $5000. Plastered interior walls, steel casement windows, 1 bath for 3 bedrooms. Narrow kitchen with refrigerator, gas oven/range and sink. The full unfinished basement had the oil fired forced air furnace, oil tank, double laundry sink, water heater and a WC. The ground foot print was about 400 sf.
That particular dbl house was repeated over a six block cluster. Average family had two to three kids with some having five. Durable starter homes for WWII and Korean War vets.
Oh... to pick nits, never ever saw a bicycle helmet offered at Sears or Western Auto, the primary purveyors of bikes in 1956. The only bike helmet I ever saw was a painted GI helmet liner worn by a neighbor called Mousie. Hell, motorcycle riders hardly wore the and the Snell Foundation hadn't started their studies.