Are others also experiencing slow delivery of post cards? Within the past decade I've noticed them averaging 7 to 10 days to be delivered anywhere but nearby. Post cards from other countries to the US are even worse, taking months to arrive, with about 25% never being delivered at all. It's become almost pointless to send "wish you were here" post cards while travelling since I return home long before the cards do.
I once sent a postcard to my grandmother here in the states while I was visiting Italy (about 3 years ago maybe) and I don't believe she ever received it. I don't know about sending postcards within the US though. I just assumed my trouble was because I was abroad. If this is true that will be too bad. I think postcards are really neat. It's a shame people don't seem to send many anymore.
The PostCrossing project publishes data, from time-to-time, on how many days/weeks it takes for postcards to travel from one country to another.
These statistics are generated by comparing the date on which the recipient's address was 'issued' to the sender with the date on which the recipient logged the postcard as arrived.
As every postcard carries a unique identifying number (otherwise unknown to the recipient) that is logged into the system by the recipient, statistics on travel time and whether/not a postcard is lost are very reliable.
Staggeringly few postcards are sent but not delivered.
Generally speaking, postcards addressed in English traveling to countries with non-Latin alphabets take the longest.