Yes, it is! If you look at the map of the North American Continent above, you will see that the United States is in green. Way up north next to Canada is Alaska, in green, still part of the continent.
So, here's a shout out to all of you shippers and businesses out there: Alaska is part of the "continental United States." Yes, we are. Every Alaskan has had the experience of ordering something through a catalogue or online and found that the shipping rate charged, i.e. the rate for the "continental United States," does not include Alaska. Having embarked on many a geographical conversation with people in other parts of the US about what constitutes a continent, I can tell you that there are many murky ideas out there about basic geography in our part of the world. (OK, I admit it - who knew that Greenland is also part of the North American Continent, but come on - Alaska is obvious.)
OK, now let's look at "contiguous," a beautiful word that I should like to use at least once a day. It means the "adjoining 48 states and the District of Columbia." The map below is the contiguous United States. Obviously, Alaska and Hawaii are not included because they are not connected geographically to the rest.
So when shippers say that shipping charges are free for the continental US, that gets our hopes up. And then our hopes are dashed when they say that doesn't include Alaska. (It also makes us wild because geography is a pretty straightforward subject and every US citizen should know where all 50 states are...) However, shippers can be geographically pure and even get back in our good graces if they stipulate "free shipping in the contiguous United States," and then we wouldn't get all excited because we would know exactly who gets free shipping and - sigh - who doesn't.