United's fleet of 767-224 aircraft is down to five units; one flies IAH
and back daily, while the other four operate across the Lake.
Today, ship 152 goes EWR
153 does an EWR
154 is doing a domestic IAH
159 is zipping from Liberty to Frankfurt.
And 160 is stuck on the IAH
routine, with an occasional turn to ORD
Other than that, Omni operates ex-CO/UA 767-224's internationally, but I don't really know much about that operation.
So US and UA
are pretty much it!