How did post-WWII federal policies contribute to US suburbanization?

Suburbanization is a process by which populations are funneled out of highly concentrated urban areas and into spaces outside of these core cities. In the United States after WWII, various federal initiatives were put in place to incentivize the movement of people (particularly white people) into the suburbs.

During the war, policy had been to concentrate production on war-related items, such as machinery and weaponry. When the soldiers returned from the war, however, they returned to find a massive housing shortage, one which would only be hastened by the post-war "baby boom." Previously, house builders might have been unwilling to embark upon mass building schemes, uncertain of people's capacity to buy houses, but a combination of factors, including high demand, meant that they felt emboldened to begin an intensive building scheme after the war. The federal policy known as the GI Bill, which guaranteed the mortgages of veterans, meant that houses could be built affordably without the builders fearing losing their investment. As a consequence, housing stock grew, and returning soldiers were able to buy these houses.

The government incentivized the house builders to construct their new developments outside of the urban centers, in the suburbs. This was chiefly done through the Interstate Highway Program, an initiative of Eisenhower's which sought to encourage expansion outside of cities and enable free travel into areas which previously might have had poor transport links. Furthermore, taxes and insurance rates were lower in the suburbs, a factor which both encouraged house builders to build there and families to buy there.

At the same time, various policies caused urban areas to be increasingly perceived as lower-class, high-crime areas, not least because they were more racially diverse than the suburbs. Real estate laws meant that it was illegal for Black people to purchase homes in some suburban areas ("redlined" areas) even if they could have afforded to. Therefore, "white flight" was encouraged, as white people chased the "American Dream" of a home in the suburbs, something from which Black people were excluded.

How did the post-WWII economic boom impact suburban development in the US?

The impact of the post-World War II economic boom on suburban development was that it had a great deal to do with causing suburbanization.

In the years after World War II, the US economy boomed.  The US was by far the richest country in the world and the one with the strongest economy in these years.  It had not been hurt by the war in any serious way and it boomed for a variety of reasons.  With the economic boom, Americans became much wealthier than they ever had been before.  This helped to bring about the development of the suburbs.

As Americans came back from the war, they had a lot of money to spend and they typically had pretty good jobs.  Because of the GI Bill, they were able to go to college in record numbers.  This helped them get better jobs.  The GI Bill also helped them get loans to buy homes in the suburbs.  Since the GI Bill did this, developers began to build suburbs to fill the demand.  The masses of new white collar workers in the booming companies filled up the suburbs.

In this way, the economic boom led to a situation in which Americans had the means to buy homes in the suburbs.