WHY YOU NEED TO KNOW HIM: Because he runs the country’s largest light-rail system, along with Dallas’ buses, commuter rail, and high-occupancy vehicle lanes. Soon after he took the helm of DART in 2002, Thomas was called “the most powerful man in Dallas” by D Magazine. The agency he leads has certainly had a profound impact on the region. Between 2003 and 2013, DART generated more than $7.4 billion in economic activity, and real estate development within a quarter-mile of its rail stations totaled more than $1.5 billion.

There’s much more to come, as transit-oriented development is entering a period of explosive growth, Thomas says, with new projects valued at nearly $4 billion. “Development is accelerating,” he says. “We’re just really starting to see some sectors recover from the economic downturn.”

Another transformational change is looming, with DART’s 14-mile Orange Line expansion to Dallas-Fort Worth International Airport slated to open later this year—a move Thomas says will “catapault Dallas to a different category, a different stratosphere.” The agency’s free D-Link buses, which travel between downtown, the Arts District, Victory Park, Uptown, the convention center, and Oak Cliff, are now up and running. A streetcar system and an expansion to the University of North Texas-Dallas campus also are in the works.

Unlike mature transit cities like Boston or New York, Dallas doesn’t have geographic constraints to growth, Thomas says, so it’s not always obvious where—or how far out—to build. Doing so in a fast-growing market has its challenges, too, he says: “We didn’t build this system for the next five years; we built it for the next 50 years.”

When he first took the job, Thomas says he didn’t realize the impact DART would have on the region. “As I look to the future, I think it’s just the tip of the iceberg,” he says. “People are just starting to embrace it now, and developers and cities are just starting to realize how they can take advantage of it.”