The nation's economic slowdown has not stopped business investment in the Triangle, even as unemployment here has hit its highest point in nearly five years.

New and expanding businesses announced more than $1 billion in new investments this summer, exceeding the total announced during all of 2007, the Research Triangle Regional Partnership reported Tuesday. The expansions announced in the past three months would create nearly 1,700 jobs in manufacturing, biotechnology, technology, health care and other fields.

Officials at the economic development group say the surge in announcements may be a coincidence but highlights the economic strength of the region.

This summer four companies -- Cheminova, Medis Medical Imaging Systems, Patheon and Tryton Medical -- moved their corporate headquarters to the Triangle, and businesses continue to contact economic development officials about moving to the area or expanding existing operations.

"It's really remarkable to have that many announcements coming in such a short period of time," said Charles Hayes, CEO of the Research Triangle Regional Partnership. "The thing that struck me was the amount of the investment -- a $1 billion increase in the tax base of the region."

The group coordinates economic development for 13 counties, including Wake, Durham, Chatham, Orange and Johnston.

The Triangle's unemployment rate in July surpassed 5 percent for the first time in four years. While layoffs contribute to joblessness, rising unemployment in the area also is caused by the high number of people moving here at a faster clip than the local economy can absorb the new workers. Transplants continue to stream into the area, which is consistently rated as a top place to live and work.

This summer's investment announcements came from 30 new and existing companies, mostly in research and manufacturing.

Michael Walden, an economics professor at N.C. State University, said the partnership's statistics bear out a familiar theme.

"People in the know -- economic developers, investors -- see this region has a solid foundation for growth," Walden said. "You'd be hard-pressed to find a region in the country that's better suited for the future than the Triangle."

Get $150+ in coupons in every Sunday N&O. Click here for convenient home delivery.