Steven, people in Europe who've paid for airmail delivery often receive their copies before people in the United States. (Their subscriptions cost a lot more!)
All copies are mailed at the same time, within a day or two of one another, from our printer in Fulton, Missouri. They are sent throughout the US by second-class periodical mail, which is used by most magazines (it's the only economically viable way to send them). But, second-class periodical mail is treated differently by every post office which handles it. Some deliver it immediately, others let it sit in the post office for weeks until they find a slow day and give it to their carriers. We have no control over it, and all magazines in our field suffer from the same type of distribution.
I could offer another category of subscriptions for those in the United States, with first class delivery, but it would add a lot to the cost of a subscription. Would you be interested?