U.S. home prices scaled new heights in April, with seven cities — including Boston, Charlotte, Portland, San Francisco and Seattle — setting record highs.

The Standard & Poor's/Case-Shiller 20-city home price index increased 5.4 percent in April compared with a year earlier, just a tick down from the 5.5 percent annual gain in March.

Shrinking inventories of homes for sale have boosted prices, while a healthy job market and historically low mortgage rates have kept demand from potential buyers strong during the months associated with the highest volume of sales.

The number of listings has fallen 5.7 percent from a year ago, the National Association of Realtors said last week. Home prices rose in all 20 major housing markets, with double-digit annual increases in Portland and Seattle.