The Free Imperial City of Cologne was recognized after 1475, thus removing it from even the nominal secular authority of the elector.

The electorate should not be confused with the Roman Catholic Archdiocese of Cologne, the area over which the archbishop exercised spiritual authority, which was larger.

Even larger was the Ecclesiastical Province of Cologne, which included suffragan dioceses such as Liège and Münster (see map below).

In 953, the archbishops of Cologne first gained noteworthy secular power, when Bishop Bruno was appointed as duke by his brother Emperor Otto I.

Eventually, the archbishop moved to Bonn to escape jurisdiction conflicts with the city government.

[2] Political tensions arose from issues of taxation, public spending, regulation of business, and market supervision, as well as the limits of corporate autonomy.

The chief cities were Cologne on the Rhine River, Hamburg and Bremen on the North Sea, and Lübeck on the Baltic.

The Reichsdeputationshauptschluss of 1803 secularized the rest of the archbishopric, giving the Duchy of Westphalia to the Landgraviate of Hesse-Darmstadt and Vest Recklinghausen to the Duke of Arenberg.