At first glance, one might think that this is just another ordinary UX55 postal card which happened to be metered because it wasn't used during the proper rate period. While true, there is a whole lot more to this card than immediately meets the eye.
The UX55 card was the 'definitive' postal card issued in 1968 to accommodate the new 5 cent postcard rate. Evidently, Michigan State University purchased a large quantity of cards and had them pre-printed with the request form seen in this example. This card must not have been used for University business by May, 1971 when the postcard rate went up to 6 cents, hence the addition of a one-cent meter imprint. This is where things get interesting.
We can see that the meter is dated July 18, 1972. Mailable matter such as this card shouldn't have been metered until the date of mailing. It further can be seen that the postmark is October 20, 1975, so technically the penny meter was invalid. The period between 1971 and 1976 was quite 'volatile', rate-wise. The postcard rate went from 6 to 8 to 7 to 9 cents in this period! The cancellation date on this card puts it in the brief 7 cent rate period of use. With a Canadian destination, the postcard rate was the same as within the United States. Now if the meter was invalid, this would make the card 2 cents underpaid. It appears that the presence of the meter coupled with the color of the card perhaps contributed to the card's successful passage in the mails (so far). The current 'definitive' card for the 7 cent rate period would have been the Charles Thompson issue, printed in a very similar shade of green.
With all of these dynamics in place, the card was still returned to sender!! The reason is entirely unrelated to the amount of postage, however. On October 23, 1975, Postal Bulletin 21061 was released to announce suspension of all service to Canada as a result of a Canadian postal strike.
This is a fascinating saga for a modern, otherwise quite ordinary postal card.
Place mouse on image to see the reverse side of the card.