COT3 is a joint venture between Clark Construction Group and W.E. O'Neil Construction. COT3 is leading the construction effort on the Terminal 3 Improvement Project, a key component of O’Hare 21, Chicago’s vision for a modern airport that will be an efficient and accessible international gateway, bringing the world to Chicago, and Chicago to the world.

This website aims to inform the public of the status of construction and provide convenient access to the latest procurement news associated with this project.