By Mark Williams
The Associated Press

COLUMBUS - When the state finishes a half-mile stretch of Interstate 670 that cuts through downtown Columbus, it will mark the end of the nearly 50-year construction of Ohio's interstate system.

"I didn't think I would live to see the day when I-670 would be finished," said Clark Street, president of the Ohio Contractors Association and a former state transportation executive.

As was the case nationally, most of Ohio's 1,300 miles of interstate were built in the 1950s, '60s and '70s.

Interstate 670, which could be completed by September, was designed as an economic development tool by making it easier to reach the northwest side of town, considered to be the city's next major growth area.

Planning for the final segment began in 1965, with construction scheduled to begin in 1976. But funding problems, the project's complexity and new environmental regulations - which prohibited the relocation of the Scioto River - stopped the project.

With a push from the state and the city, planning resumed, with the initial work completed in 1993. The last two projects began last year, one of which involves rebuilding a segment constructed in the 1960s. The total cost for the project is $200 million.

"We've had to overcome a lot to get to this point. Now, there's a clear sense of excitement that we're nearing the end," said Michelle May, an Ohio Department of Transportation spokeswoman.

Nationally, there are just a few sections to be finished before the 42,800-mile interstate system is completed, said Richard Weingroff, a spokesman for the Federal Highway Administration. The remaining projects include completion of the "Big Dig" Interstate 93 project underneath Boston, and parts of a link for Interstate 95 north of Philadelphia.