"Those are the main factors driving the gains in men. For women, those same things also are important but also reductions in heart disease mortality," Harper said from Montreal.

He and his co-authors studied data from the U.S. National Vital Statistics System to try to figure out what was behind the closing of the life expectancy gap that began to be apparent around the mid-1990s.

Life expectancy in the United States has been on the rise since at least the late 19th century. But for as long as life expectancy rates have been broken out by race and ethnicity, the average life expectancy of blacks has been shorter than whites.

Blacks made progress toward closing the gap in the 1970s and early 1980s, but those gains were reversed by the spread of HIV-AIDs and an increase in homicide rates from about 1984 onward.

Since 1993, the article says, the gap has narrowed to historic levels, declining to 5.3 years in 2003 from 7.1 years in 1993.

Further narrowing the gap will require efforts to address the differences in outcomes between blacks and whites afflicted with cardiovascular-related diseases, HIV and infant mortality, and further lowering the homicide rate among blacks, the authors say in the paper, published in the Journal of the American Medical Association.

"The good news is that we've made some progress over the past decade. But there's still a long way to go," Harper said.

"If there's bad news, the bad news is that we saw that heart disease trends among older black males were not favourable. And those continued to keep the gap too far."

"The heart disease mortality rates for black men are going down. But they're just not going down as fast as they are for white men."

The study doesn't look to see if there are any differences in life expectancy between blacks and whites in Canada.