Dodd, Jordan, Liahona Research, comp. Illinois Marriages, 1790-1860 [database on-line]. Provo, UT, USA: The Generations Network, Inc., 2004. Original data: With some noted exceptions all marriage records in this collection can be found at the Family History Library in Salt Lake City, Utah, or available through Family History Centers throughout the United States. For specific source information listed by county see the extended description above or the see the source information listed for each entry.
I have found some records here that are not represented on the Source:United States, Illinois, Illinois Statewide Marriage Index, 1763-1900.
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