Black and white wing seen from below.

A fairly large bird. Somewhat smaller than a crow. I’ve seen it twice and in Indianapolis, but only as it flew overhead. The under side of the wings is a pure black in both the front and back, each about 1/3 of the wing length, with a pure white, zigzag pattern on the front and back. The white is approximately 1/3 of the total length. length. It’s quite striking.
Never seen anything like this. Can’t find it in any bird book.
Help!