The 1790 - 1840 censuses only listed the head of household and then number of each other house-member in each age group.
I did not find a person named Mantle in the 1820 census in either Baltimore or Harford Counties Maryland.
There is an Eli Mantle in Baltimore, Baltimore Co, Maryland in the 1830 census. He is between the ages of 30-39, married with one daughter. United States Census, 1830; https://familysearch.org/ark:/61903/3:1:33SQ-GYY1-SQRF?cc=1803958&wc=35YC-MVP%3A1588471003%2C1588471007%2C1588471010 He was married in Harford Co, Maryland in 1824 to Catherine Logue.
In the 1810 Census there is a Levy Mantle, between ages 16-26, in Baltimore, Baltimore Co, MD. In addition to Levy there is a male, between ages 10-16, and two females, one between ages 16-26 and one 45 or older. Ancestry.com - 1810 United States Federal Census
In the 1800 Census there is a William Mantel, between the ages 16-25, living in Harford Co. MD. There are 3 children under the age of 10 in household. 1800 United States Federal Census - Ancestry.com
Dear Mr. Mantle,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the Population Schedules for the 1820 Census in the Records of the Bureau of the Census (Record Group 29) that may contain information about the family of Eli Mantle For access to the non-digitized schedules, please contact the National Archives at Washington, DC - Textual Reference (RDT1) via email at firstname.lastname@example.org.
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For information about the U.S. Census, see the Census Bureau technical documentation and questionnaires. Even though the census before 1850 only listed the head of the household by name, and the rest of the family members by sex & age, you can often use that information to infer the individual’s relationship. See NARA’s Clues in Census Records, 1790-1840 for more information.
You may wish to search Ancestry.com or FamilySearch.org for the U.S. Census. There may be a fee for using Ancestry. Instead, please check for access at your local library as many library systems subscribe to these sites, making them free for their patrons.
We hope this is helpful. Best of luck with your family research!
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I checked familysearch.org in the 1920 United States Census
The following link shows how many persons by the name Mantle were listed
familysearch.org is a free website, you just need to register to use.