It is getting more difficult to afford a home in America. According to a report from ATTOM Data Solutions, a real estate and property data provider, median home prices in 2018’s fourth quarter hit their least affordable levels in over a decade.

That quarter, homes sold for a median price of $241,250, a 9% increase from the fourth quarter of 2017, while the average annualized weekly wage in the United States of $56,381 climbed by only 3%. However, home prices actually became more affordable in 58% of counties over that same period.

For many Americans, owning a home is financially unrealistic. In some counties, the median home price is more than four times higher than what someone could afford based on the area’s average earnings.

24/7 Wall St. reviewed information from ATTOM Data Solutions on income needed to buy a home and average annual wages in each county to determine America’s 25 least affordable housing markets. The income needed to buy a house is calculated by assuming a 3% down payment and a 28% maximum “front-end” debt-to-income ratio.

The 25 least affordable housing markets in the United States are clustered in just four states — Massachusetts, Hawaii, New York, and California. All seven New York counties are either in or just outside New York City. The 15 least affordable California housing markets are spread out across the state.

To determine the 25 least affordable housing markets in the United States, 24/7 Wall St. reviewed county-level data from ATTOM Data Solutions. Counties were ranked based based on the affordability ratio — median housing prices in the area relative to average annual wages. Home sale price data and the total number of housing units also came from ATTOM. The income needed to buy a house is calculated by assuming a 3% down payment and a 28% maximum “front-end” debt-to-income ratio.

Click here to see America’s least affordable housing markets.