I saw this image and have been trying to figure out a way to create the same. The shading particularly has me confused.
The irregularities and inconsistencies in the shading make me think this was hand inked then scanned in and digitized.
It's a style that was very common in the 60s and 70s before everything was done on computers. It's also what comic book artists used to do up until tablet technology became good enough to emulate pen and paper.
A lot of times graphic designers would use tracing paper and ink and use a photo for reference. This gives you the variety in line quality that you see. There are programs that you can now use to do this on a computer, but they generally involve a sensitive tablet so you can get the hand-drawn effect. Painter is one of them.
There are Illustrator and Photoshop filters out there that you can apply to a photo to get this, but they're all bunk in my opinion. I haven't seen any that can get real artwork like the example you've provided.
I think you've already chosen a picture that you want to create in this style. Open that picture in Photoshop. First, desaturate your picture. Then go to Image -> Posterize and chose level: 1. Now you see a one level shadow in your picture.
Place that picture in Illustrator, and draw the shadows as shown on your posterized picture. After that, you can make the shading stripes like the poster with the blob brush.
I think this is the only way to do it.