Home prices rose in May for the second straight month as federal tax incentives pulled more buyers into the market.

The Standard & Poor's/Case-Shiller 20-city home price index released Tuesday posted a 1.3 percent increase in May from April.

Nineteen of 20 cities showed price gains month over month. Minneapolis and Atlanta led the way with 2.8 percent and 2 percent increases, respectively. And San Diego posted its 13th straight monthly gain.

Only Las Vegas recorded a price decline. The metro hit a new record low in May. Home prices there have lost 56.4 percent of their value since peaking in August 2006.

And while Detroit recorded a 0.7 percent increase from April, the average home price there is about same as it was in 1994.

Overall, the gains underscore the impact of the government's homebuying tax credits. Buyers rushed to purchase before the credits expired at the end of April. The index is an average of home sales in March, April and May.