DALLAS - Residents of three overwhelmingly Hispanic counties along the Texas-Mexico border enjoy some of the longest life spans in the state.

Details are in a Harvard University study.

Hidalgo and Cameron counties ranked first and second in residents life expectancy, living an average of 80.3 and 80.1 years, respectively.

Neighboring Starr County was fifth, with an average life expectancy of 79.6 years.

A professor at the University of Texas at Austin said the phenomenon is part of what some demographers and public health experts call the "Hispanic paradox."

David Warner is an economist who's studied health care issues among Mexican-Americans.

Warner says even though Hispanics have less access to health care, even though they don't use health care too much and even though they have relatively lower incomes - they seem to live longer.

Williamson County and Collin County each reported an average life span of 79.7 years to complete the top five.

- By contrast, residents of Anderson County had the shortest average life expectancy at just 72 years.

- Overall, Texas is 30th in the nation with an average life span of 76.7 years.

Hawaii (80 years) is first, while Mississippi (73.6 years) is last among states, although Washington D.C (72 years) is last overall.