The Ambassador Bridge is a privately-owned toll bridge linking Detroit MI with Windsor ON. Google Maps shows no route numbers assigned to the US side, but highway 3 to the Canadian side.
Are there any other privately-owned toll highways, tunnels, or roads in the US or Canada which have highway numbers attached to them? ON-407 ETR would be one. That would exclude roads such as the Mt. Washington Auto Road (NH), and the Pikes Peak Highway (CO).
I’m pretty sure that the Dulles Greenway is Virginia State Route 267.
Also the Indiana East-West Toll Road is designated I-90 for its entire length, and I-80 for part of it. But I think it’s owned by a state agency and only operated by a private company.
Yes, but there are several important qualifiers to that. It’s numbered as a provincial 400-series highway partly based on its original intent to be a free public expressway just like all the other 400-series expressways. It was only later that part of it was privatized, which was never originally planned. The privatized part is now called the 407 Express Toll Route, or 407-ETR, and it continues east from the Pickering area as Ontario Highway 407, and also west for a short distance just before you get to Burlington where it merges with the QEW…
The Chicago Skyway is private.
I had not driven it in a while until last year. I got a toll to get on. Then got a toll to get off. That surprised me.
I gather the Brooklyn Bridge is also frequently on the market…
The Lake of the Ozarks Community Bridge in central Missouri is privately owned and financed by tolls, and will be until the construction bonds are paid off. It’s designated as County Road MM.
California State Route 91 had some high occupancy express lanes built by a private company who then transfered ownership to the state which in turn leased them back to the company to operate and collect tolls. But just a few years later the a state agency bought back the operating rights. There was a controversial provision in the original contract that prevented the state from improving the rest of the road to drive up toll usage on the privately held lanes.
Orchard Pond Parkway near Tallahasee FL is designated as County Road 0344.
Texas SR 130 (The Pickle Parkway) is publicly owned, but build by a private firm who has a contract to collect the tolls for 50 years.
And, to the OP’s question, is part of Interstate 90’s route through Chicago’s south side.
The Skyway is actually owned by the City of Chicago, which built it, though a private consortium signed a 99-year lease with the City in 2004, to operate the Skyway (and collect the tolls).
And, due to a quirk in the Chicago laws at the time, it’s a bridge with very along approaches, not a highway. They weren’t allowed to build toll roads, but they could build toll bridges.
The upper half of the Raleigh, North Carolina outer beltway is government owned I-540 with no toll. The lower half is a privately owned toll road, which is designated as NC540.
Etc Chicago skyway is my preferred route to LSD, the industrial view of the steel mills flaring off in the distance is not to be missed however it starts out as an Indiana toll road and there is no toll free toll roads aka just drive on through the toll free lanes and catch up with Chicago toll
Authority create an account and get billed nickels and dimes to drive the roads. It’s automatic thereafter. If Indy got on board with toll free it’d be 
100 % better than cash or cc frustration at the unmanned antiquated booths of the Chicago skyway I love you butt!!!
Ambassador going to Canada perfection as near as possible.
Return to US and it’s loop de loop rackety wrack, unfinished construction
The decision to label private road with apparently public road designators is complicated,
but one factor is practicality… is it common sense ?
If the privately owned road allows a public road to continue, then the privately owned road might get the apparently public label.
The I75 continues past the end of the bridge.
The I96 ends at its junction with the I75… That junction is also where where the spaghetti junction for the Ambassador Bridge is… so it might be possible to say the bridge carriers the I75… But it serves no particular benefit… Drivers might mix it up with the M85, which also passes by the same spaghetti junction.
On the canadian side, their Highway 3 runs straight up at the bridge. Highway 3 is just a few miles long though, but it is continuous with Highway 401 which is good to get to the east of the lake shores in Canada. (Toronto,etc)