WASHINGTON -- The number of workers who died on the job fell by 17 percent last year to the lowest level in nearly two decades, as workers logged fewer hours during the recession, the Labor Department said Thursday.

The 4,340 workplace fatalities recorded in 2009 was the smallest total since the Bureau of Labor Statistics first began tracking the data in 1992. It's the second straight year that fatal work injuries have reached a historic low, following a 10 percent drop in 2008.

High unemployment and layoffs in more dangerous industries like construction played a major role in the decrease, the agency said. The construction unemployment rate is 17.3 percent, nearly double the overall jobless rate of 9.5 percent.

Workers on average logged 6 percent fewer hours last year than in 2008. Employees in construction worked 17 percent fewer hours in 2009 than the previous year.

As a result of the recession, the building trade has "fallen off a cliff," said Ed Priz, president of Riverside, Ill.-based Advanced Insurance Management, a consulting firm. "It reflects a shift in the kind of work Americans are doing. There are a lot less hazardous jobs."

Workplaces in South Carolina were safer during 2009 with 73 fatal work injuries recorded, the smallest number tallied since record-keeping began in 1992. A report by the South Carolina Department of Labor Licensing and Regulation said Thursday that 87 worker deaths were recorded in 2008.

The agency said its biggest decline came in the transportation and material-moving occupations, where fatal incidents declined 36 percent. There were 28 deaths in those areas in 2008 and 18 in 2009.

Labor Secretary Hilda Solis called the nationwide decrease in on-the-job deaths encouraging and pledged to continue her agency's stepped-up enforcement of workplace safety laws.

"As the economy regains strength and more people re-enter the work force, the Department of Labor will remain vigilant to ensure America's workers are kept safe while they earn a paycheck," Solis said.

Workplace suicides declined by 10 percent to 237 after reaching a historic high in 2008. But that count is still the second-highest total recorded since the agency began tracking workplace deaths.

For the second straight year, commercial fishing was the deadliest occupation in the country, with a fatality rate about 60 times higher than the average rate for all workers.

One of the few sectors where the fatality rate increased was in building and grounds maintenance, where the number of deaths rose 6 percent.

The report is based on preliminary numbers. A final report is scheduled to be released next year.

In other findings:

--Transportation incidents, which accounted for nearly 40 percent of all work fatalities last year, fell 21 percent from 2008.

--Fatalities among black workers declined 24 percent. Black employees also saw a larger decline in the number of hours worked than white or Hispanic workers.

--Workplace homicides declined 1 percent to 521 cases. That is nearly half the all-time high of 1,080 homicides recorded in 1994.

Bloomberg News contributed to this report.