U.S. home prices rose 2.4 percent in May, with the Seattle metro area showing its largest monthly gain since April 1990, according to a leading index.

The Seattle market, which includes King, Pierce and Snohomish counties, posted a 3.1 percent gain from April to May in the S&P/Case-Shiller 20-city home-price index released Tuesday.

The index recorded its best year-over-year gains since March 2006. It was also the first time any city in the index reached a new all-time high: Dallas and Denver surpassed previous peaks before the financial crisis.

All 20 cities saw home prices rise over the month and over the year.

Half the cities saw home price increases accelerate, led by Chicago, where prices rose 3.7 percent over April.

Twelve metro areas posted double-digit growth over the past 12 months. San Francisco’s home prices increased the most, 24.5 percent, followed by Las Vegas, where prices rose 23.3 percent. The Seattle market showed an 11.9 percent gain.