Across the United States, real estate is becoming too expensive for residents, even in what were recently considered some of the country's most affordable cities.

To find where residents are being priced out of housing markets where they could once manage to buy, financial site SmartAsset analyzed national data and ranked the cities by percent change in home value to household income ratios.

Researchers found that "many once-affordable markets are trending toward scenarios where residents are housing cost-burdened," meaning some people are forced to spend more than the government-recommended 30 percent of their monthly gross income on housing.

Here are the top 10 once-affordable cities where residents are being priced out: