Koffee
If it helps, at McCormick and green bay there is no trail but If you go North on green bay like 2 to 3 miles you can hop over the tracks and there's a road that runs along to green bay but on the other side of the tracks.
So at this point you’re north bound on the green bay trail but there is no marked trail until you hit the train station in Wilmette. Don't think I don't like riding by the lake or on Sheridan but if you want the green bay trail you don't need to go any further east.

So I gotta ask what ride are you going on? Is there a loop? Have you been on the other trail that runs along the 94 up thru the Skokie lagoons and in to the baticanal gardens?