Kansas City, Mo ? Congress gave final approval Wednesday to a plan to move 6,000 Internal Revenue Service workers into a redeveloped area in and around the downtown Kansas City post office, Sen. Kit Bond said.

The $300 million plan calls for renovation of the 70-year-old postal building and construction of three office annexes west of the post office. The building has been partially empty since 1999, when postal workers were shifted to another location.

The 4,000 permanent and 2,000 seasonal IRS workers will move from other sites across the Midwest to a Regional Service Center at the postal office, which is across the street from Union Station. The post office’s retail counter will move to a location inside Union Station.

“This project has the potential to serve as a strong economic engine that can help power the Kansas City downtown economy for a long time,” Bond said.