CHAMPAIGN, Ill. — Healthy mass transit systems could contribute to healthier communities, according to a new study by University of Illinois researchers that determined higher mass transit use was correlated with lower obesity rates in counties across the United States.

“As local communities seek to allocate public funds to projects that will provide the most benefit to their residents, our research suggests that investing in convenient and affordable public transit systems may improve public health by reducing obesity, thereby providing more value than had been previously thought,” said Sheldon H. Jacobson, a professor of computer science at Illinois. He conducted the study with graduate student Zhaowei She and Douglas M. King, a lecturer of industrial and enterprise systems engineering.

The study used publicly available county health and transportation data. To get the clearest picture of the relationship between mass transit use and obesity, the researchers controlled for a number of factors that could influence health or transportation, such as household income, poverty rate, education level, leisure physical activity and access to health care among the adult residents of each county.

“By viewing this link at the county level, we provide a national perspective by considering data from counties throughout the United States,” King said. “Our research suggests that, in addition to benefits to the environment and greater access to transportation for residents, community-level investments into public transit systems may also benefit public health by reducing obesity rates.”

The analysis found that for each 1 percent increase in a county’s population who frequently ride public transit, obesity rates dropped 0.2 percent. The study is published in the journal Preventive Medicine.

The latest findings correlate well with previous work by Jacobson and King that found a reduction in daily driving, even by a mile a day, was associated with a reduction in body mass index.

“The choice to ride public transit instead of driving can create an opportunity for physical activity,” Jacobson said. “For example, when someone rides a bus, they may begin their trip by walking from their home to a bus stop before boarding the bus. Then, once they get off of the bus, they may still need to walk from a bus stop to their destination. Alternatively, if they had driven a car, they might simply drive directly from their home to their destination and eliminate the walking portion of the trip.”