1884 June 5:
Clark Island post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1949 October 26 through 1950 April 22:
The circular postmark is 32–33 mm in diameter. The outside vertical height of the four bars to the right of the circle is 19 mm.
1961 May 26:
Clark Island post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
Glenmere
1892 December 21:
Glenmere post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1931 July 10:
The circular postmark is 31–32 mm in diameter. The outside vertical height of the four bars to the right of the circle is 18–19 mm.
1942 November 14:
Glenmere post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
Port Clyde
1880 February 3:
Port Clyde post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1948 December 3 through 1950 December:
The circular postmark is 32–34 mm in diameter. The outside vertical height of the four bars to the right of the circle is approximately 20 mm.
2020:
Port Clyde post office 2020. 860 Port Clyde Road; Port Clyde, Maine 04855. Lat./Long.: N 43°55′38″ x W 69°15′26″
today:
Port Clyde post office is still in operation.
Saint George
1828 February 8:
Saint George post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1903 September 15:
The circular postmark is approximately 18 mm in diameter.
1933 May 30:
The circular postmark is 32–33 mm in diameter. The outside vertical height of the four bars to the right of the circle is approximately 19 mm.
1937 December 20:
The circular postmark is approximatelu 34 mm in diameter.
1991 November 29:
The outer circle of the postmark is 30–31 mm in diameter; the inner, 20–21 mm.
1993 May:
Saint George post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
Tenants Harbor
1853 September 15:
Tenants Harbor post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
2020:
Tenants Harbor post office. 4 Main Street; Tenants Harbor 04860. Lat./Long.: N 43°58′02″ x W 69°12′28″
today:
Tenants Harbor post office is still operating.