This chart shows the availability of the U. S. Federal Census for Mercer County searchable online. Of course, they are available on microfilm at various libraries. For earlier years, use the census for Mercer County's parent counties.
| Census Year | Microfilm No. | Status | Index | Transcription | Images |
|---|---|---|---|---|---|
| 1840 | M704 | Available | USGenWeb. Ancestry.com [subscription fee]. | Ancestry.com [subscription fee]. | USGenWeb. Ancestry.com [subscription fee]. |
| 1850 | M432 | Available | Ancestry.com [subscription fee]. | Ancestry.com [subscription fee]. | Ancestry.com [subscription fee]. |
| 1860 | M653 | Available | Ancestry.com [subscription fee]. USGenWeb [partial]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. USGenWeb [partial]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1870 | M593, T132 | Available | Ancestry.com [subscription fee]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1880 | T9 | Available | FamilySearch.org. Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. | FamilySearch.org. Ancestry.com [subscription fee]. USGenWeb [partial]. HeritageQuest Online [subscription fee]. | FamilySearch.org. Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1890 | Destroyed | ||||
| 1900 | T623 | Available | Ancestry.com [subscription fee]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. Genealogy.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1910 | T624 | Available | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1920 | T625 | Available | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. USGenWeb [partial]. | Ancestry.com [subscription fee]. HeritageQuest Online [subscription fee]. |
| 1930 | T626 | Available | Ancestry.com [subscription fee]. | Ancestry.com [subscription fee]. | Ancestry.com [subscription fee]. |