Single-family homes sales in Houston shot up 30% in August, sending a dose of economic optimism through the nation’s fourth-largest city. The Houston Association of Realtors said 6,524 homes were sold last month among all property types. The total dollar volume for all the properties sold increased 29.4% to $1.34 billion from $1.03 billion a year earlier. The trade group said Houston’s “rosy performance” looks even better when compared to the lackluster results of the summer of 2010, which came right after the homebuyer tax credit expired. Still, August was the third consecutive month with a sales increase and the fourth time sales remained positive in a given month this year. Buyers were not discriminate in August. HAR said sales rose in every housing category, from home less than $80,000 to properties worth $500,000 or more. Year-to-date, sales are up 1.8% and foreclosure sales are 26.2% higher than 2010. The median price of Houston foreclosures sold in August declined 5.4% from a year earlier to $80,375. Write to Kerri Panchuk.