Here in Milwaukee we have hundreds of different kinds of wors to choose from. The locals call them "Brats" (pronounced as in afrikaans brats not brets). They boil them in water(par boiled) then grill it, they par boil them in beer and onions, they grill them ens. ens. ens.
Some are pretty good some are horrible. Most are pork. My local butcher do have pork and beef so I get them there.
I like Usinger's.
You can read all about the brats history here Wikipedia Brat Page
Here is a a snippet.
"In the United States, bratwurst, while not strictly a regional cuisine, is strongly identified with areas where German and other Northern European immigrants settled in large numbers, such as Sheboygan, Wisconsin, which is informally known as the "Bratwurst Capital of America". The city celebrates "Sheboygan Bratwurst Days", a community festival held on the first Thursday through Saturday of August each year. Bratwurst is especially popular in a region stretching from Chicago, Illinois up through Wisconsin into Minnesota and the Upper Peninsula of Michigan; Milwaukee, Wisconsin is also a center of bratwurst appreciation. Johnsonville Foods, the nation's largest bratwurst maker, is based in Sheboygan Falls, Wisconsin. Other traditional Wisconsin brat manufacturers include Klement's Sausage Company and Usinger's, both of which are based in Milwaukee.
The city of Madison, Wisconsin, holds an annual festival billed as the "World's Largest Brat Fest". The four-day charity event sees tens of thousands of brats sold by "celebrity" cashiers, usually local television, radio, and government personalities. Brat Fest's self-proclaimed world record is 191,712 brats consumed during the 2008 event. Throughout Wisconsin, the "brat fry" is a popular fundraising technique; brats are grilled outdoors and sold for the benefit of a charity organization."