That's CDN

The cost of mailing a first-class letter within Canada will increase to 54 cents from 52 on Monday.

Postcard to Canada

$0.72

Letters To Canada

1 oz. : $0.72
2 oz. : $0.96
3 oz. : $1.20
3.5 oz. : $1.44

USPS Site

Current Cost

First Class Domestic Letter: $.42

New Rate Increase

As of today, the rate for a first class domestic letter will increase from $.41 to $.42.

Wonderfully Comprehensive List of Price Increases

With a beginning date of 1863 (!) Andrew K. Dart has compiled a list of postage increases throughout the years.