According to the 1880 U.S. Census record for son Reuben, John McCullough was born in MD and Reuben's mother was born in PA.


http://freepages.genealogy.rootsweb.com/~millergonzalez/mccullough.html


This December, 2001 letter excerpt, sent to my grandmother by Ken Bowers, describes a connection between Reuben McCollough and John McCullough of southern Lancaster County.


================================================================================================================================================
CENSUS YEAR: 1800    STATE: PA    COUNTY: Lancaster    TOWNSHIP: Dromore    MICROFILM#: M32-39    ENUMERATOR: Jonathan Morre
================================================================================================================================================
       |                                                    |FREE WHITE MALES   |FREE WHITE FEMALES |ALL    |      |
       |                                                    |    10  16  26     |    10  16  26     |other  |      |
       |HEAD OF HOUSEHOLD                                   |to  to  to  to  45 |to  to  to  to  45 |free   |      |
PG#    |LAST NAME             FIRST NAME                    |10  16  26  45  up |10  16  26  45  up |Persons|Slaves|Remarks
================================================================================================================================================
. . . . .
164     McCollough            John                           .   1   1   .   1   .   1   2   .   1   1       .
. . . . .



==========================================================================================================================================
CENSUS YEAR: 1800    STATE: PA    COUNTY: Lancaster    MICROFILM#: M32-39    ENUMERATOR: Jonathan Morre
==========================================================================================================================================
    |                                            |FREE WHITE MALES   |FREE WHITE FEMALES |ALL    |      |
    |                                            |    10  16  26     |    10  16  26     |other  |      |
    |HEAD OF HOUSEHOLD                           |to  to  to  to  45 |to  to  to  to  45 |free   |      |
PG# |LAST NAME         FIRST NAME                |10  16  26  45  up |10  16  26  45  up |Persons|Slaves|Remarks
==========================================================================================================================================
. . . . .
227  McColough         George                     .   2   .   1   .   1   .   1   1   .   .       .
. . . . .


==========================================================================================================================================
CENSUS YEAR: 1800    STATE: PA    COUNTY: Lancaster    MICROFILM#: M32-39    ENUMERATOR: Jonathan Morre
==========================================================================================================================================
    |                                            |FREE WHITE MALES   |FREE WHITE FEMALES |ALL    |      |
    |                                            |    10  16  26     |    10  16  26     |other  |      |
    |HEAD OF HOUSEHOLD                           |to  to  to  to  45 |to  to  to  to  45 |free   |      |
PG# |LAST NAME         FIRST NAME                |10  16  26  45  up |10  16  26  45  up |Persons|Slaves|Remarks
==========================================================================================================================================
. . . . .
241  McCullough        Samuel                     .   1   .   .   1   3   .   .   1   .   .       .
. . . . .


Based on the page number, the township for Samuel and George's census records above would be Strasburg, Martick, Bart, or Ropho.


FIRST U.S. CENSUS OF PENNSYLVANIA 1790
U.S. Government Printing Office 1908
Drumore Township, Lancaster County

Column 1 and 2  Head of Household
Column 3 Free white males, 16 and upward including head of household
Column 4 Free white males under 16 years of age
Column 5 Free white females, including head of household
Column 6 All other free persons
Column 7 Slaves

Column 1 2 3 4 5 6 7
--------------------
. . . . .
McCulloch George 1 0 0 0 0
McCulloch John 4 3 4 0 0
McCulloch William 1 1 4 0 0
McCullough Alex 2 1 6 0 0
. . . . .