> Metra which spreads into northern Indiana

You're thinking of the South Shore Line [0], which is entirely independent of Metra [1] and the RTA.

> and Southern Wisconsin

Metra has just one stop on one line in Wisconsin (Kenosha on the Union Pacific North line).

[0]: http://www.mysouthshoreline.com/

[1]: https://metrarail.com/maps-schedules/system-map

You are correct, but the planned extension of the CTA Red Line includes a new station that is shared with the South Shore, creating a brand-new connection ability that never existed before. The planning for the new Union Station to McCormick Place link involves connecting the CTA, Metra and South Shore lines.

If you are standing in downtown Chicago, you can jump onto a train and conveniently go to O'Hare International (Blue Line CTA), Midway International (Orange Line CTA), Milwaukee International (Amtrak), and South Bend Regional (South Shore). South Bend has daily non-stops to NYC so I'm not sure why it's called a regional airport, but, well, there you go.

I'm confused by what possible efficiencies can be generated by connecting the Red Line and the South Shore line. I presume that most riders on the SS line are commuting to work in or near the Loop. The SS line is undoubtedly faster than the Red Line. Furthermore, there's already Metra lines in existence around the area of the proposed Red Line extension.

Furthermore, I'm not sure what good a Union Station to McCormick Place link would do. Union Station is already within a 20 minute walk to every single CTA/Metra/SS line. Furthermore no one really lives/works near McCormick Place. It's primarily a convention center.

It has an express, and it still counts.

Although it really sucks when someone misses the correct train and you have to drive to Winthrop Harbor to pick them up.