House listings in 26 different US metropolitan regions declined on a month-over-month basis for the 15th straight month, according to real estate brokerage ZipRealty (ZIPR). The total number of single-family homes and condos listed for sale decreased 1.8% from August to September, bringing the total number of active listings to 642,308. On a year-over-year basis, the US housing inventory is down 27.1%. Austin, Texas and Los Angeles had the greatest percent decrease in inventory from August to September at 4.7% each, followed by Las Vegas (4.4%), Orange County (4%) and Miami (3.5%). Boston's inventory grew the most (2.2%), followed by Baltimore (1.5%) Sacramento (1.3%) and Charlotte (0.2%) as the regions surveyed with increases in inventory. The data is based on multiple listing service records ZipRealty compiled at the end of the month and does not include the shadow inventory of already foreclosed homes banks haven’t released to the market. Write to Austin Kilgore.