1892 November 18:
Convene post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1935 September 18:
The four horizontal bars at the right of the “circle” are approximately 6 mm apart on center.
1955 June 30:
Convene post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
Douglas Hill
1902 February 17:
Douglas Hill post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1935 September 18:
The circular postmark is 30–31 mm in diameter.
1965 June 3:
The circular postmark is 32–33 mm in diameter.
1972 January 28:
Douglas Hill post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
East Sebago
1876 January 15:
East Sebago post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1937 June 19:
The circular postmark is 32–33 mm in diameter.
1948 August 11:
The four horizontal bars at the right of the circle are approximately 6 mm apart on center.
1965 February 4:
The circular postmark is 32–33 mm in diameter. The outside vertical height of the four horizontal bsrs to the right of the circle is 19–20 mm.
today:
East Sebago post office is still in operation.
Hillside
1897 July 17:
Hillside post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1937 December 13 through 1948 November 1:
The circular postmark is 32–33 mm in diameter.
1955 July 1:
Hillside post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
North Sebago
1884 May 8:
North Sebago post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
1935 September 18:
The circular postmark is approximately 33 mm in diameter. The four horizontal bars at the right of the “circle” are approximately 6 mm apart on center.
1964 May 8:
North Sebago post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
Sebago
1829 January 5:
Sebago post office opened. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)
year? June 5:
Manuscript postmark.
1940 April 2:
The circular postmark is 30–31 mm in diameter. The outside vertical height of the four horizontal bars at the right of the circle is approximately 18 mm.
1940 April 30:
Sebago post office closed. (source: Maine Philatelic Society. 1995. The Post Offices of Maine: A Rarity Guide)