With the recent discussion about the NHL's realignment plans, I thought it would be fun to look at where professional hockey was many years ago. 1926-27 was the first season that the modern major-league/minor-league structure was put in place. In addition to the 10-team NHL, which resulted from the absorption of the rival Western Hockey League, there were four professional minor leagues:
The American Hockey Association arose from the Central Hockey League, which was a semi-professional league that itself arose from the western section of the United States Amateur Hockey Association (Duluth, Minneapolis, St. Paul), plus the Winnipeg Maroons. A team was added in Chicago, and the former Sault Ste. Marie club moved to Detroit for the 1926-27 season.
The Canadian-American Hockey League was essentially brand-spanking new for the 1926-27 season. It featured teams in Boston, Springfield, New Haven, Providence and Quebec City, and had the greatest overlap in territory with the NHL.
The Canadian Professional Hockey League was a result of the professionalization of a bunch of Ontario Hockey Association senior clubs: Hamilton, London, Niagara Falls, Stratford and Windsor.
The Prairie Hockey League arose from the remains of the Western Hockey League, and was geographically the most isolated of all the professional leagues (unless you count the California league, which was not affiliated to the rest of the leagues in any way). It included teams in Calgary, Edmonton, Regina, Saskatoon and Moose Jaw, Saskatchewan.
Here's a little map to summarize: