The US is about 5 million houses underbuilt. Here are some of the reasons why: Covid-19 has increased the desirability of homeownership. Millennials are entering peak homebuying age so demand will remain elevated for years. Anti-development attitudes make it very tough to build. Supply-chain problems and the high prices they create prevent entry level homes from being built. Households have ample wealth to spend on housing, and rates remain low.