WASHINGTON (AP) _ The nation's unemployment rate held steady at 4.5 percent in July, withstanding the sharp but temporary impact of the General Motor strikes, which produced the worst factory job losses in 16 years.

It matched June's rate and was only slightly higher than the 28-year low of 4.3 percent, reached in May, the Labor Department said today.

However, U.S. employers reported a net gain in jobs of only 66,000, the weakest month in two and a half years. Job growth was held back by a drop of 176,000 in manufacturing, the largest since October 1982.

The department attributed 146,600 of the loss to the direct or indirect impact of the GM strikes, which began June 5 with a shutdown at a metal stamping plant in Flint, Mich., and were settled last week.

Auto manufacturing alone suffered a drop of 111,000 jobs but other industries that supply GM, the nation's largest corporation, were forced to lay off their workers.