The list of markets that qualify as "improving" according to the National Association of Home Builders/First American Improving Markets Index ticked down in May, moving to a total of 100 markets from 101 in April.

The index—which lists markets once they have shown improvement from their respective troughs in housing permits, employment, and home prices for at least six consecutive months—dropped 18 metro areas from the list and added 17 new ones. With the exception of one market, the drops came as a result of prices dipping below their previous troughs.

"The overall number of markets on the IMI continued to plateau this month, with more than a quarter of all U.S. metros still showing signs of improvement," wrote David Crowe, chief economist at the NAHB, in a release today. "Many of these are relatively small markets in terms of their population and building volume, which is why their improvement is barely registering on the national scale as of yet."

Notable new additions in May include Phoenix; Bend Ore.; and Lubbock, Texas. Overall, 34 states and the District of Columbia have at least one metro area listed.

To see the NAHB’s full press release, click here.

Claire Easley is a senior editor at Builder.

Learn more about markets featured in this article: Phoenix, AZ, Bend, OR, Lubbock, TX, Greenville, SC.