The Leading Economic Index has fallen in three of the past six months, but rose 0.5 percent in July, which was checked by a 0.5 percent drop in June.
The drop for August was in line with the consensus forecast.
The index, which takes into account 10 economic components, is essentially a comparison with 2004, the year the Conference Board assigned a level of 100.
July's improvement was boosted by "positive contributions from the financial components," including stock prices and yield spread, said Conference Board economist Ataman Ozyildirim.
"Over the last several months, the U.S. LEI seems to be fluctuating around a flat trend, while strengths and weaknesses among its components remain balanced" he added in a statement.
Conference Board economist Ken Goldstein said the economy "continue(s) to be buffeted by strong headwinds domestically and internationally."
"As a result, the pace of growth is unlikely to change much in the coming months," he said. "Weak domestic demand continues to be a major drag on the economy."