The rule of thumb on how much a person should budget for rent is 25% to 30% of monthly income. But due to inflation in property values and surging demand, affordable housing is increasingly becoming a pipe dream in some states.

Among the most expensive rental markets is the nation’s capital, where a person must make an average of $8,487 a month to rent, according to cost estimating site HowMuch.net.

In California, the richest state in the U.S. based on gross domestic product, the monthly income to afford renting a house is $8,313, followed by Hawaii at $7,806 and New York at $7,223.

HowMuch.net

In contrast, in several states in America’s heartland and in the South, a person can make less than $3,500 a month and be able to make rent.

“Based on the rule of applying no more than one-third of income to housing, people living in the Northeast must earn at least twice as much as those living in the South just to afford rent for what each market considers an average home,” said HowMuch.net’s Raul Amoros.

Affordability is a challenge in places like California—whose economy is the fifth largest in the world if it was an independent country. The state’s median household income is roughly $67,000 a year, comparatively higher than most other areas, but there is still a huge gap between its median income and the $99,756 a year needed to pay rent.

“Even in a comparatively well-off state, over half the population is considered unable to adequately afford an average rental,” Amoros said.

Much of the problem stems from steep property prices and tight supply — and the situation is not likely to improve much in the short term.

HowMuch.net compiled its data by calculating the average price of a rental property in each state and then applying no more than 30% of monthly net income for rent.