Ancestry.com's about the database article for the 1810 United States Federal Census asserts:
Partial losses included Illinois Territory, which had only two
counties (Randolph is extant, St. Clair is lost.), and OH, all lost
except Washington County.
If the Washington County, Ohio schedules exist, then how can we find the schedules? Failing that, how can we find out who might be in those schedules that were not lost?
- Searching the collection directly on Ancestry.com with no name, and with a location "Ohio, USA" with exact search yields no matches.
- Ohio is not listed in the drop-down under "browse these records", so apparently Ancestry doesn't have the images for Ohio online either.
- The FamilySearch description for the collection 1810 US Federal Census says "No schedules are known to exist for District of Columbia, Georgia, New Jersey, Ohio, and Tennessee. Index provided by Ancestry.com." and the Wiki article United States Census, 1810 (FamilySearch Historical Records) agrees: " No schedules are known to exist for District of Columbia, Georgia, New Jersey, Ohio, and Tennessee. Index provided by Ancestry.com."
- The mouse-over descripton in the Ancestry Card catalog about the 1810 census says "Published on Ancestry 1/13/200; Updated 6/19/2013". They claim to have 830,631 records.
- The FamilySearch entry for the 1810 census says "826,307 records, last updated 01 Feb 2012".
- A no-name search on FamilySearch.org, restricted to United States and Ohio, yields 15 entries in the collection list, none of which is the 1810 Census.
This suggests to me that if either Ancestry or Family Search has the population schedules for Washington County, Ohio, they either aren't published yet or they aren't indexed.
The National Archives and Record Administration's list of Microfilm Publications and Original Records Digitized by Our Digitization Partners says that 1810 Census was digitized by Ancestry.com and is part of Record Group 29, publication number M252.
However, searching for the publication number "M252" returned a list of Microfilm Available in the Reference Room: Census Records from the Laguna Niguel, CA branch:
- 1810 Third Census M252 1
- 1810 Census for Washington County, OH M1803 1
The NARA Series to FHL film Conversion on Family Search says:
M1803 Roll 1 2155489
Plugging that into the catalog yields this result:
Nonpopulation census schedules for Baltimore City and county,
Maryland, 1850-1860 : agriculture, industry, and social statistics
As you can see, sometimes FamilySearch has a little problem with their citations of NARA Microfilm reels.
The real catalog entry at FamilySearch is here: Third census of the United States, 1810, population schedules, Washington County, Ohio (M1803). This gives a digital film number of 2155490. There is no link to an online collection at FamilySearch.org, so the collection isn't online, but you can order the film to be viewed at your local Family History Center.
The notes say:
Includes townships of Adams, Belpre, Fearing, Grand View, Marietta,
Newport, Roxburg, Salem, Warren, Waterford, Wesley, and Worcester.
Lists name of head of the family and age brackets of other members of
Arranged in alphabetical order by township.
The USGenWeb Census project has some indexes for Washington County, Ohio available, and they are seeking transcribers for others.
The FamilySearch Wiki article Ohio Population Schedule Indexes: Fiche, Film, or Book lists the following for 1810:
- Ronald Vern Jackson, Ohio, 1810 : U.S. federal census index (WorldCat) and U.S. federal census index, Ohio, 1810 [FHL Book 977.1 X22ja 1810]
- Sue Powell Morgan, U.S. federal census index, Ohio, 1810(South Jordan, UT : Genealogical Services, 2003, ©2000).
See also the Ohio State Library/Archives for more information and holdings for records which can be used as substitutes.
Ancestry.com's card catalog also has listings for records which can be used as a census substitute:
For more ideas about where to find other records, you could search WorldCat for guides such as William Dollarhide's Census substitutes & state census records : an annotated bibliography of published name lists for all 50 U.S. states and state censuses for 37 states. (Note that there are two volumes: Volume 1: Eastern States and Volume 2: Western states.) There is a library locator where you can enter your zip code to find books in a library near you.