The U.S. postage required to mail a first-class letter from Texas to Vancouver, Canada is $1.15, according to the United States Postal Service. This rate only applies to letters weighing up to 2 ounces.
Postage for letters weighing over 2 ounces but not more than 3 ounces is $1.61. The postage on more than 3 ounces is $2.08. The maximum weight allowed on first-class, international letters to Canada is 3.5 ounces. Letters exceeding this amount are charged international flat-rate prices.
There are dimensional limitations as well. International letters cannot be longer than 11.5 inches or higher than 6.125 inches and no thicker than .25 inch. Moreover, the value of the contents cannot exceed $400.