The laying claim to the Midwest thing isn't really true. They sure had a right to set up shop wherever they wished, but not all the Midwest families answered to them.

-St. Louis answered to Kansas City until 1960, which answered to Chicago. But Tony Giordano hated Chicago and if he answered to anyone it was Detroit, who was his closest ally.
-LA never answered to Chicago, and neither did San Francisco or San Jose.
-The Smaldones were closest with St. Louis but I'm not sure with them
-Dallas answered to New Orleans (is Dallas Midwest)?

In the end yes, Milwaukee, KC and the minor Rockford family answered to Chicago. And that counted for a lot, but it wasn't everything, it wasn't a Midwest takeover. The greatest right Chicago had was to open up shop anywhere in the Midwest that wasn't taken.