1860 United States Federal Census
Name: John W Leighton
Age: 10
Birth Year: abt 1850
Birth Place: New Hampshire
Home in 1860: Farmington, Strafford, New Hampshire
Household Members:
Name Age
Moses C Leighton 43
Hannah Leighton 38
George Leighton 15
Charles H Leighton 13
John W Leighton 10
James F Leighton 9
Mark F Leighton 8
William S Leighton 5
Augustus F Leighton 3
Clara A Leighton 6

New Hampshire, U.S., Marriage Records Index, 1637-1947
Name: John W Leighton
Marriage Date: 16 Oct 1876
Event Type: Marriage
Marriage Place: Farmington, Strafford, New Hampshire
Birth Date: abt 1849
Birth Place: Farmington, New Hampshire
Age: 27
Father's Name: N Channey
Mother's Name: Hannah
Spouse Name: Jennie M Tebbette
Spouse Birth Place: Farmington, New Hampshire
Spouse Age: 25
Spouse Father's Name: Alvin
Spouse Mother's Name: Eliza J
FHL Film Number: 1001276

1880 United States Federal Census
Name: John W. Leighton
Age: 31
Birth Date: Abt 1849
Birthplace: New Hampshire
Home in 1880: Farmington, Strafford, New Hampshire, USA
Relation to Head of House: Self (Head)
Marital status: Married
Spouse's Name: Jennie Leighton
Father's Birthplace: New Hampshire
Mother's Birthplace: New Hampshire
Occupation: Works In Shoe Shop
Household Members:
Name Age
John W. Leighton 31
Jennie Leighton 29
Alta F. Leighton 2
Edith E. Tibbetts 10

New Hampshire, U.S., Death and Disinterment Records, 1754-1947
Name: John W Leighton
Birth Date: abt 1848
Birth Place: Farmington, New Hampshire
Father: Moses C Leighton
Mother: Hannah Tanner
Death Date: 8 Oct 1920
Death Place: Farmington, New Hampshire, USA
Age at Death: 72

Added bio info by Diana Smith (49355335):
The death record indicates a birth date of 20 August. There is a copy of the original birth record attached to the file on Family Search (https://www.familysearch.org/tree/person/details/KZKM-V8W) which clearly shows a 10 August birth date. I suspect the death record is a duplicate since it was typed.