Washington ? Manufacturing flashed another growth signal in September and construction spending climbed in August to the highest level in seven months, a double dose of encouraging news for the economy and Wall Street investors.

Mike Eckler, of D&D Masonry in Rensselaer, N.Y., uses a boom truck to remove concrete forms from a basement in a new housing development being built in Cohoes, N.Y. The Commerce Department reported Wednesday that construction spending climbed in August to the highest level since the beginning of the year.

The Institute for Supply Management reported Wednesday that for the third month in a row, activity at America’s factories expanded. The research group’s manufacturing index was 53.7 in September, compared with 54.7 in August.

An index reading above 50 indicates expansion; one below 50 indicates that manufacturing activity is contracting.

Jerry Jasinowski, president of the National Association of Manufacturers, called September’s index reading “a strong indicator that manufacturing is gaining momentum.”

In a second report, the Commerce Department said the total value of building projects under way came in at a seasonally adjusted annual rate of $882.7 billion in August — the strongest showing since January — and a 0.2 percent increase from July.

Contributing to August’s increase were spending on housing by private builders and spending by the government on public works projects. Each had its best month on record. Those gains blunted losses elsewhere.

“Housing continued to streak ahead, public construction rebounded but private nonresidential construction slipped again,” said Ken Simonson, chief economist at Associated General Contractors of America.