It has been closed for six days after three technicians tested positive for COVID-19 last week.
RELATED: Midway Control Tower workers test positive for coronavirus; hundreds of flights canceled at airport
Flight operations were limited during the closure and the Federal Aviation Administration said they put a ground delay program in place allowing flights to operate on a "one-in-one-out" basis.
The FAA said the tower has been thoroughly cleaned and other workers are still being evaluated.
RELATED: Southwest reduces service to and from Midway
Southwest Airlines, which has the most flights into and out of Midway, had greatly reduced its schedule while the tower was closed.