Here are some interesting covers from Dannemora, NY, the site of the recent escape from the Clinton Correctional Facility in June, 2015. Dannemora is in Clinton County, NY. The post office was established January 17, 1850 and is still in operation.
A Nesbitt envelope from the 1850s:
An octagon with a negative star killer (1879?):
A red circular date stamp with a nice star killer (1880):
There have been a number of postmaster in the last 165 years:
James H. Gibson Postmaster 01/17/1850
Herman Lowry Postmaster 04/06/1853
James H. Van Aranam Postmaster 08/11/1856
Heber S. Lewis Postmaster 03/21/1861
Loring Chappel Postmaster 06/23/1863
John H. Hopkins Postmaster 06/07/1871
Charles H. Stackpole Postmaster 02/12/1875
Seth Allen Jr. Postmaster 01/10/1884
James P. Cunningham Postmaster 07/23/1885
Seth Allen Jr. Postmaster 07/23/1889
James P. Cunningham Postmaster 05/09/1894
Seth Allen Postmaster 06/18/1898
Joseph S. Nash Acting Postmaster 04/12/1912
James H. Signor Acting Postmaster 04/16/1912
James H. Signor Postmaster 05/24/1912
Philip White Signor Acting Postmaster 10/05/1914
James H. McCorry Postmaster 03/13/1915
Robert J. Fitzpatrick Postmaster 03/15/1916
Louis H. Buck Postmaster 01/05/1922
Karl L. Whipple Acting Postmaster 05/01/1930
Karl L. Whipple Postmaster 12/18/1930
Jacob Tolosky Acting Postmaster 01/31/1935
Jacob Tolosky Postmaster 08/02/1935
Lewis O. Carter Acting Postmaster 06/30/1958
Donald J. Fitzpatrick Acting Postmaster 06/09/1961
Donald J. Fitzpatrick Postmaster 12/02/1963
Lawrence H. Douglas Officer-In-Charge 06/30/1973
Lawrence H. Douglas Postmaster 09/29/1973
Audrey M. Douglas Officer-In-Charge 10/01/1992
Audrey M. Douglas Postmaster 12/12/1992
Christine Trombley Officer-In-Charge 03/19/1997
Kevin E. Goddeau Postmaster 08/16/1997
This information comes from the USPS's Postmaster Finder webpages.