Elections were held annually from 1837 through 1921, biennially from 1923 through 1933, and quadrennially starting in 1935.
Members of the Council are known as alderpersons, (some prefer the terms alderman, alderwoman, or alder) and are elected from districts known as wards.
Prior to that time the number of wards varied but they were almost always entitled to two alderpersons each.
Chicago's incorporation as a city in 1837 abandoned such a model in favor of a Common Council elected from wards and a separate mayor elected at large.
However, the mayor would serve as the presiding officer of the Common Council.