Built in 1957 as the Will Rogers Turnpike, it runs from the Oklahoma/Missouri State Line near Joplin to Tulsa where it joins OK 66 and US 412. In 1958, the turnpike was "grandfathered" in to the Interstate highway system as I-44.
In 1992, the Oklahoma Turnpike Authority built the Creek Turnpike, a partial loop around Tulsa. Its northern (or West) end was at I-44 northeast of Tulsa, with its southern (or East) terminus at I-44 near Sapulpa. Following the completion of the turnpike, I-44 was rerouted along a 2 1/2 mile section of the turnpike, which left a 2 mile section of the original highway abandoned. I-44 now enters Tulsa co-signed with US 412.
These first two photos show the north approach to the lane shift
Abandoned lanes. Look closely in the second photo and you can see an exit sign for OK 66.
Looking Northwest from OK 66, plus abandoned roadway at OK 66
Here's a Google satellite view to put it all in perspective:
It's not totally abandoned, though: the Oklahoma Highway Patrol is said to use this for training grounds. Plus, I think a State Senator used it as part of an ad for how bad Oklahoma highways were and how he would fix everything if elected (he lost).