Wow, Steve Blust is right in his post below. INTERNATIONAL (but not national -- mailing within the US) rates have just about DOUBLED for first Class Parcels (but not for letters). For example, a three ounce parcel from the US to Canada used to be $3.30; it is now $7.35 -- as noted in the charts below.
(But a 3 ounce LETTER from the US to Canada went up only from $1.49 to now $1.55.)

In the two pages below:
¶ the first class LETTER rates are on the top of each page (the rates don't show the 20-cent surcharge needed for each letter when you send chips). The first class PACKAGE (PARCEL) rates are on the bottom of each page.
¶ Each set of rates shows four price groups: the first column is Canada, next is Mexico, then Groups 3-5 (Europe, Australia, etc.) and finally Groups 6-9 (New Zealand, etc.).

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The old rates (began January 2012):
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The new rates beginning Jan 27, 2013:
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Robert