U.S. home prices climbed steadily in July even as sales slowed, evidence that a supply shortage of houses for sale is distorting the real estate market.

The Standard & Poor's CoreLogic Case-Shiller national home price index rose 5.9 percent in July from a year earlier, slightly faster than June's 5.8 percent annual pace.

Sales of both new and existing homes slipped over the summer, which typically might slow price gains.

But demand remains strong and has created bidding wars among potential buyers, pushing up prices at a much faster pace than incomes. The number of existing homes for sale fell 6.5 percent in the past year.

Seattle, Portland, Oregon and Las Vegas saw the largest increases, with prices in Seattle soaring 13.5 percent in July from a year earlier.

Other cities are also seeing strong gains. Home prices rose 7.3 percent in Dallas and Detroit, and 7.2 percent in Denver. The slowest increases were in Washington, D.C. and Chicago, which both reported 3.3 percent gains.

With unemployment low and paychecks rising modestly, more people are in the market for a home. But construction of new single-family homes has been held back by a limited supply of land in hot markets and difficulty in finding construction workers.

That has intensified the competition in the housing market. Homes sold after an average of just 30 days on the market in August, according to the National Association of Realtors, down from 36 days a year ago.

Hurricanes Harvey and Irma began to pinch sales in August and should drag on the sales in the months ahead.

The Case-Shiller index covers roughly half of U.S. homes. The index measures prices compared with those in January 2000 and creates a three-month moving average. The July figures are the latest available.