The way the Catholic Church is organized within the United States can be confusing. Some areas are called dioceses, while others are archdioceses. What is the distinction between a diocese and an archdiocese and why is Milwaukee — and the 10 counties surrounding it — considered an archdiocese?

The answer is simpler than one may think.

The Catholic Church is made up of clusters of dioceses called “ecclesiastical provinces.” The largest diocese by population in that ecclesiastical province is called an archdiocese, and is led by a bishop who is called the archbishop. He can also be called the “metropolitan.” Milwaukee, the city with the largest population in the 19th century, was chosen to be the site of the center of the Church in the state of Wisconsin.

The history of the Archdiocese of Milwaukee goes back to 1843. The number of Catholics in Wisconsin in 1843 was growing, along with the populations of Catholics in other “western” areas of the country. The bishops of the United States at that time met and appointed Bishop John Martin Henni as the bishop of the Diocese of Milwaukee. This diocese was large; it included the entire state of Wisconsin and various parts of Michigan and Minnesota.

In 1866, a council of bishops was gathered again, and this time, discussion about making the Diocese of Milwaukee into the Archdiocese of Milwaukee arose. However, Milwaukee was denied the status. Historian and Wisconsin native Fr. Peter Leo Johnson speculated that Milwaukee was not made an archdiocese because of the happenings in Chicago that year.

By 1866, there were more than a quarter of a million Catholics in Chicago. The bishop of Chicago had a psychological episode and was placed in a mental asylum, and therefore, could not be made an archbishop. If Chicago could not be made an archdiocese, then the thought of Milwaukee becoming an archdiocese was out of the question.

Two years later, Bishop Henni wrote Pope Pius XI to create two new dioceses from the Diocese of Milwaukee: the Diocese of Green Bay and the Diocese of La Crosse. Today, there are four dioceses that came from the original Diocese of Milwaukee: the Diocese of Madison, the Diocese of Superior, the Diocese of Green Bay and the Diocese of La Crosse. These are called “suffragan dioceses” and are not part of what is today the Archdiocese of Milwaukee. They are governed by their own bishops, and the archbishop of Milwaukee has no governance function over these dioceses.

In 1875, Bishop Henni was created the archbishop of the Archdiocese of Milwaukee, the archdiocese that we know, love, and call home today.