ST. LOUIS — Every Tuesday morning, Teri Dobbins-Baxter starts her commute at 4 a.m.

She leaves home in the south suburbs of Chicago and goes to Midway Airport, where she hops a flight to St. Louis. Then she makes her way to St. Louis University, where she works as a law professor. She then spends two days teaching and meeting with students, and flies home Wednesday night.

The ranks of people like Dobbins-Baxter, who live in one metropolitan area but work in another, are growing fast. Technology continues to untether employees from their workplaces, while the weak job market and a lousy housing market have many families reluctant to relocate.

A study issued last month by New York University found that the jobs with this sort of arrangement climbed sharply in eight of 10 large metro areas from 2002 to 2009.

Some of these people work from home for companies in a different region. Some are traditional road warriors who travel all over. Some, like Dobbins-Baxter, have a regular commute – just one that spans states instead of a county line.

Regardless, said Mitchell Moss, the NYU professor who authored the study, the trend speaks to both the increased flexibility of modern-day workers — “the office” can be almost anyplace — and the challenges facing two-income families in a weak job market: Why uproot your family when your spouse can’t get a job in the new city?

The trend illustrates how the economies of places like St. Louis are increasingly hitched to their neighbors.

“It tells you that there is an inter-regional economic relationship, which is growing between places like St. Louis and Chicago,” Moss said. “A region’s workforce is not defined by its immediate suburbs.”

It also has implications for the people who live and work this way. Take Dara Taylor.

She works for a Boston-based health care policy nonprofit, from her apartment in the Central West End. She’s from St. Louis, where her boyfriend and family live. About a year and a half ago, she became the nonprofit’s first remote employee.

“Everything I do is by phone or email or by travel,” said Taylor, who has worked for the organization for ?two years. “Because that’s the case, I can work from another city.”

So Taylor spends a lot of time on Skype and conference calls with colleagues from the home office. She travels two or three times a month to other states and occasionally back to Boston. In some ways, ?this arrangement is more ?flexible, but Taylor said she finds it forces her to be more efficient.

Then there are those for whom the road is the office. Jason Stokes lives in St. Louis but works in quality improvement for a Dallas-based company that makes pumps and seals for oil wells and power plants. He visits projects all over the world.

“Last year I spent 190 nights in hotel rooms,” he said by phone from Los Angeles, where he was wrapping up a three-week stint before heading to Virginia and then India.

All these things — family, housing, the complexity of managing two careers in a weak job market — are big reasons why this sort of two-city existence is growing.

Add in employers who ?are willing to be more flexible and technology that en-?ables it, and Moss said he expects that growth will continue.