Demand for office space in the United States reached its highest level in nearly four years in the second quarter, the St. Louis Business Journal reported.

The amount of space being leased minus the amount that becomes available – otherwise known as net absorption – increased to 12.8 million square feet during the second quarter, according to Cassidy Turley research.

That marked the largest gain since the third quarter of 2007. The figures represented the fifth consecutive quarter of positive net absorption.

In the Midwest, positive net absorption reached 417,000 square feet during the second quarter, after registering in negative territory of 417,000 square feet during the three months ended March 31.

“It was encouraging, but we all know that commercial real estate lags the economy,” said Kevin Thorpe of Cassidy Turley’s Washington office. “We are certainly tempering our enthusiasm going forward. What we are really projecting here is that the U.S. economy will continue to move in fits and starts. We see this as a slow-growth scenario.”

According to Real Capital Analytics, sales of office properties rose 126 percent during the first five months of 2011, compared with the year-earlier period. The average price per square foot was $211, a 25 percent increase from last year.

Office rents in the Midwest increased slightly in the second quarter to $18.33 a square foot, compared with $18.29 a square foot in the first three months of 2011.