The $93.5 million project was completed in Will County thanks to the Rebuild Illinois Capital Plan.
Governor JB Pritzker said the interchange will create a more efficient transit experience and boost local economy in Will County.
Illinois 59 will continue to be reduced to one lane in each direction approaching Seil Road through late October. Additional lanes on the ramps will also open by the end of the month.
The public will continue to see delays as construction crews clean up the construction site.
Before the interchange, only NB I-55 could exit to NB Illinois 59 and from SB Illinois 59 to SB I-55.
With the ramps opening, both directions of I-55 can access both directions of Illinois 59 and vice versa.
Officials also said East Frontage Road was relocated and reconstructed. This provided distance from the interchange, with auxiliary lanes added to I-55 between Illinois 59 and U.S. 52.
To read more about the Rebuild Illinois Capital Plan, click here.
New I-55 interchange at Illinois 59 opens