__
                                                 |  
                            _Robert MCCORMICK ___|
                           | (1738 - 1818) m 1770|
                           |                     |__
                           |                        
 _Robert MCCORMICK Jr______|
| (1780 - 1846) m 1808     |
|                          |                      __
|                          |                     |  
|                          |_Martha SANDERSON ___|
|                            (1747 - 1803) m 1770|
|                                                |__
|                                                   
|
|--Cyrus Hall MCCORMICK Sr
|  (1809 - 1884)
|                                                 __
|                                                |  
|                           _____________________|
|                          |                     |
|                          |                     |__
|                          |                        
|_Mary Ann McChesney HALL _|
  (1780 - 1853) m 1808     |
                           |                      __
                           |                     |  
                           |_____________________|
                                                 |
                                                 |__