This is the first in a series of three posts aimed at answering the question, "Where should I look for vital records?"
For marriages, in short, (no matter what an index search may tell you about availability), you can get licenses from 1871 to 1941 online through FamilySearch by visiting a Family History Center or an affiliate library. After that, you'll need to contact the Cook County Clerk's Office for the records.
Unlike birth and death records, marriage licenses were numbered consecutively without starting over. So, if you have a license number, you can easily pick a "film" from the record groups linked below and play the high/low number game to zero in on the right image. If you have a film number and an image number, you can go right to the document. And, if you have neither, all is not lost. If you have a marriage date, browse to find the licenses issued on that day and then work backwards from there. Generally, couples married the same day or a few days after getting the license.
|Record Groups Accessible from the FamilySearch Catalog
||Indexes to these Records|
|Marriage licenses, 1871-1920; index, 1871-1916
||Illinois Statewide Marriage Index, 1763-1900
Results provide license number
Results provide film number and image number
Results provide film number
|Illinois, Cook County, marriage records, 1920-1950
See https://chicagogenealogy.blogspot.com/2017/11/cook-county-marriage-licenses-creative.html for information on how record groups are arranged in the Family History Library catalog entry.
|Cook County, Illinois Marriage Indexes, 1912-1942
Results provide license number; index is not complete (no “Smith” entries beyond 1933 in search results, for example)
|Illinois, Cook County, marriage records, 1950-1964
||Cook County, Illinois Marriage Index, 1930-1960
Results provide “file” number (license number)