Interesting. I thought maybe it came from their history. I mean the USA were "founded by sailors", and that is why it would be more prominent.
But yeah I saw some videos that american use the mercator projection regualry, and I personally never saw it before. ^^
Generally it gets cut off in most world maps (so you don't see all of mega-Antartica/Greenland). So you very well may have, you just don't recognize it. The Mercator has a lot of first mover advantage, since it was an early development (back in the 16th century) and useful for navigators (who were the only people who most needed maps for a good chunk of history), and so got used for centuries before alternatives were really developed. As such, it's one that lots of people are familiar with; if you see a rectangular-shaped map of some kind, odds are very good that it's a Mercator. Google Maps and MapQuest, for example, both use a modified version of the Mercator Projection.
Even if you are used to a different projection, they all have distortions of some kind.
And America has a very long seafaring tradition. While the Mayflower is the most famous, almost all the colonies were founded by colonists who sailed from England (and being poor sailors had nothing to do with their survival problems, which had more to do with being poor farmers). More to the point, the US (specifically New England), became a major maritime power very early, to the point that the British hired privateers to target American merchant shipping even during the American Revolution. Though I find it unlikely that that has much to do with the popularity of the Mercator.
