DENVER—For Janessa White, the American dream of a red brick house on a tree-lined street blocks from a good elementary school remains obtainable. She just has to rent it.

Ms. White and her boyfriend moved with her 7-year-old son from Missouri to Denver last year. In Missouri, Ms. White owned her home, which she bought for a little over $100,000. To buy a house like the one she rents in Stapleton, an affluent section of the Colorado capital, would cost about four times as much. Even though her household’s income is in the low six-figures, homeownership is daunting in Denver.

“It’s hard not to want to buy,” she said. “Saving for a huge down payment seems almost impossible.”

Ms. White’s household is part of a growing camp: high-earning Americans who are renting instead of buying homes. In 2019, about 19% of U.S. households with six-figure incomes rented their homes, up from about 12% in 2006, according to a Wall Street Journal analysis of Census Bureau data that adjusted the incomes for inflation. The increase equates to about 3.4 million new renters who would have likely been homeowners a generation ago.

“I can’t think of anyone we’ve rented to recently who didn’t make $100,000,” said Bruce McNeilage, who owns 148 rental homes around the Southeast and is building 118 more.