Reference:
U.S. International Postal Rates, 1872 - 1996, Wawrukiewicz, A. and Beecher, H., CAMA Publishing Company, Portland Oregon,1996
When the newly formed Dominion of Canada's Post Office Act came into effect on April 1, 1868, the rate to and from the United States was 6 cents per 1/2 oz. on prepaid letters and 10 cents per 1/2 oz. on unpaid letters.
Paid
a) Stamped
Montreal to New York, June 9, 1868
6 cents prepaid letter rate to the United States
Kingston to Portland, CPnn., April 26, 1873
6 cents prepaid 1/2 oz. letter rate to the United States
b) Stampless
Postage stamps were not required for franking until October 1, 1875.
St. Athanase, Quebec, to Plattsburgh, December 16, 1873
6 cents prepaid 1/2 oz. letter rate to the United States
Unpaid
Allanburg to Belleville, N.Y., September 18, 1871
10 cents unpaid 1/2 oz. letter to the United States
U.S. "DUE 10" handstamp
A reduced letter rate agreement, effective February 1, 1875, provided that letters mailed in Canada to the United States and vice versa, were to be fully prepaid at the domestic letter rates of the country of origin, and the country of destination received, forwarded, and delivered the letters free of charge. The unpaid letter rate was abolished.
a) Stamped
Montreal to Dingmans Ferry, Pa., August 18, 1879
3 cents 1/2 oz. letter rate to the United States
b) Stampless
The use of postage stamps became compulsory in Canada on October 1, 1875.
St. Johns, Quebec, to Norwich, Conn., September 27, 1875 (late date)
3 cents 1/2 oz. letter rate to the United States
Toronto to West Liberty, Iowa, April 27, 1891
3 cents per ounce letter rate to the United States
The letter rate was reduced to 2 cents for each ounce.
Ottawa to Bisbee, Arizona, December 24, 1901
2 cents per ounce letter rate to the United States
Winnipeg to Cincinnati, November 16, 1906
2 cents per ounce letter rate to the United States
Halifax to New Haven, May 15, 1914
2 cents per ounce letter rate to the United States
War Tax Period I (1915- 1926)
A war tax of 1 cent was imposed only on the first ounce letter rate and not on subsequent weight steps. The tax could be paid using War Tax stamps or ordinary postage stamps.
Toronto to New Haven, August 11, 1915
2 cents postage + 1 cent War Tax paying the letter rate to the United States
Letters mailed without the prepaid War Tax were to be returned to the sender for payment of the War Tax. When the sender was not known, the letter was to be endorsed "War Tax" and sent to the Dead Letter Office (D.L.O.).
Bawle. Alberta, to Broooklyn, November 13, 1916
1 cent War Tax unpaid
No return address so letter forwarded to D.L.O. Toronto where 1 cent stamp affixed to pay the tax.
1Tc War Tax stamp : 2 cents postage + 1 cent War Tax paying the letter rate to the United States
Montreal to New York, July 31, 1937
1Tc War Tax stamp : 2 cents postage + 1 cent War Tax paying the letter rate to the United States
Montreal to Binghampton, N.Y., January 13, 1921
3 cent stamp : 2 cents postage + 1 cent War Tax paying the letter rate to the United States
Montreal to Los Angeles, May 31, 1926
3 cent stamp : 2 cents postage + 1 cent War Tax paying the letter rate to the United States
Removal of War Tax (1926 - 1931)
The War Tax was removed in 1926.
Montreal to Boston, March 28, 1927
2 cents letter rate to the United States
Windsor to Detroit, March 12, 1927
2 cents letter rate to the United States
Toronto to New York, October 29, 1928
2 cents letter rate to the United States
Sault Ste Marie to Worcester, August 26, 1930
2 cents letter rate to the United States
War Tax Period II (1931 - 1943)
The 1 cent War Tax was reimposed in 1931.
Toronto to Leominster,
3 cents paying the 2 cent letter rate + 1 cent War Tax to the United States
Montreal to Flushing, February 10, 1934
3 cents paying the 2 cent letter rate + 1 cent War Tax to the United States
Crystal Beach to Buffalo, May 28, 1936
3 cents paying the 2 cent letter rate + 1 cent War Tax to the United States
Sherbrooke to Hudson Falls, N.Y., May 13, 1937
3 cents paying the 2 cent letter rate + 1 cent War Tax to the United States
Winnipeg to Washington, March 23, 1943
3 cents paying the 2 cent letter rate + 1 cent War Tax to the United States
War Tax Period III (1943 - 1951)
The War Tax was increased from 1 cent to 2 cents for the 1st ounce.
Revelstoke to Oakland, April 1945
4 cents paying the 2 cent letter rate + 2 cent War Tax to the United States
Toronto to Oswego, N.Y., August 1, 1951
4 cents paying the 2 cent letter rate + 2 cent War Tax to the United States
First Weight Step Letter Rate Incorporates War Tax
The first weight step letter rate incorporated the war tax making the letter rate 4 cents for the first ounce and 2 cents for each additional ounce. There was no effective change in the letter rate.
Ottawa to Portland, February 1, 1953
4 cents letter rate to the United States
Alfred to Pacoima, Calif., December 4, 1953
4 cents letter rate to the United States
The surface letter rate to the United States was increased to 5 cents for the 1st ounce and 3 cents for each additional ounce.
5 cents surface letter rate to the United States
Port Credit to Wellesley, Mass., June 15, 1966
5 cents surface letter rate to the United States
Black Harbour to Proctor, Vermont, October 30, 1968
5 cents surface letter rate to the United States
The surface letter rate was 6 cents for the first ounce and 4 cents for each additional ounce.
Virgil to Chicago, June 20, 1969
6 cents surface letter rate to the United States
Prince Albert to Peoria, December 19, 1970
6 cents surface letter rate to the United States
The letter rate was increased to 7 cents for the first ounce and 5 cents for each additional ounce.
Downsview to New York, July 27, 1971
7 cents surface letter rate to the United States
Hull to Holland, Michigan, June 9, 1973
8 cents surface letter rate to the United States
Calgary to Buffalo, May 3, 1974
8 cents surface letter rate to the United States
The surface/ air mail letter rate distinctions were abolished. All letter mail to the United States was forwarded the most expeditious way. The rate for all letter mail to the United States was 10 cents for the first ounce and 9 cents for each additional ounce.
Richmond, B.C., to Jackson, Miss., January 17, 1977
10 cents all-up letter rate to the United States
Aylmer West to Portland, Oregon, April 22 1976 (7:00 am cancellation)
8 cents affixed originally, thus shortpaid 2 cents
The letter was returned to the sender for additional postage:
2 cents added (Macdonald definitives) and cancelled at Aylmer West, August 22 1976 (10 p.m. cancellation)
The letter rate was 12 cents for the first ounce and 10 cents for each additional ounce.
Lachine to Milwaukee, October 11, 1977
12 cents letter rate to the United States
The rate was 14 cents for the first ounce and 12 cents for each additional ounce.
Kapuskasing to New York, July 31, 1978
14 cents letter rate to the United States
The rate was 17 cents for the first ounce and 14 cents for each additional ounce.
Mississauga (L4W 1T0) to Sun City, Ca., May 1, 1979
17 cent letter rate to the United States
Letter weights were now measured in grams. The first weight step was up to 30 grams.
Macamic to Holland, Mich., November 21, 1981
17 cents 30 g. letter rate to the United States
Toronto (M4L 3T0) to Tamarac, Florida, September 17, 1982
35 cents 30 g. letter rate to the United States
Kazlo to Daly City, Ca., July 6, 1984
37 cents letter rate to the United States
Kingston, N.S., to Arlington, Va., December 4, 1986
39 cents letter rate to the United States
Forwarding label affixed
Meteghan River, N.S. to Mount Clemens, Mich., December 10, 1987
42 cents letter rate to the United States
Rouyn- Noranda to Belmont, Mass., June 7, 1988
43 cents letter rate to the United States
Salmon Arm to Anderson, In., July 4 1989
44 cents letter rate to the United States
Scarborough to Clearwater, May 19, 1990
45 cents letter rate to the United States
Comox to Palmyra, N.Y., December 23, 1991
46 cents letter rate to the United States
Port Colborne to Buffalo, November 9, 1992
48 cents letter rate to the United States
Beauvallon, N.B., to Indianapolis, July 16, 1993
49 cents letter rate to the United States
Nanaimo to Longview, Wash., April 11, 1995
50 cents letter rate to the United States
Toronto to Chicago, May 1, 1998
52 cents letter rate to the United States
Saint John to Chicago, December 1, 2000
55 cents letter rate to the United States
Guelph to Midlothian, Va., December 18, 2001
60 cents letter rate to the United States
Sackville to Mislothian, Va., September 13, 2003
65 cents letter rate to the United States
Cover not shown
Brampton (Toronto LPP) to Safety Harbor, Fla., December 2005
85 cents letter rate to the United States
Clavet, Sask., to Clive, Iowa, January 27, 2006
89 cents letter rate to the United States
Toronto to Thorndale, Pa., March 1, 2007
93 cents letter rate to the United States
Corner Brooke to Concord, N.H., October 22, 2008
96 cents letter rate to the United States
Vancouver Olympic Games definitive
Vancouver LPP to Los Angeles, September 11, 2009
98 cents letter rate to the United States
Ste Rose du Lac, Man., to Los Angeles, August 10, 2010
$1.00 letter rate to the United States
Cover not shown
Toronto to Austin, November 12, 2012
$1.05 letter rate to the United States
Cover not shown
Guelph to Midlothian, Va., December 18, 2001
60 cents letter rate to the United States
Sackville to Mislothian, Va., September 13, 2003
65 cents letter rate to the United States
Cover not shown
Brampton (Toronto LPP) to Safety Harbor, Fla., December 2005
85 cents letter rate to the United States
Clavet, Sask., to Clive, Iowa, January 27, 2006
89 cents letter rate to the United States
Toronto to Thorndale, Pa., March 1, 2007
93 cents letter rate to the United States
Corner Brooke to Concord, N.H., October 22, 2008
96 cents letter rate to the United States
Vancouver Olympic Games definitive
Vancouver LPP to Los Angeles, September 11, 2009
98 cents letter rate to the United States
Ste Rose du Lac, Man., to Los Angeles, August 10, 2010
$1.00 letter rate to the United States
Cover not shown
Toronto to Austin, November 12, 2012
$1.05 letter rate to the United States