From UA's company news feed:
The FAA has restored full air traffic operations at Chicago Center in Aurora, Illinois. As of 8 a.m. Monday, ORD was operating with an AAR (aircraft acceptance rate) of 106, the normal rate for the current airport configuration; however, a significant weather system over the middle of the country will bring the airport's rates back down lower tonight and into tomorrow. During the outage only 64-80 aircraft were allowed in the airspace per hour.
The center was damaged on Sept. 26, forcing numerous cancellations and forcing all airlines to reduce schedules dramatically. In the past two weeks, we have worked with the FAA and our teams in the Network Operations Center and at ORD to match our flying levels with the available airspace capacity.