Learning New Things

Now, I'm not normally considered a stupid guy. When someone accuses me of being smart though I usually reply that it's not that I'm smart so much as I'm paying attention. So when I don't know something it's probably because I've never run across the information before. And here's something I ain't never run across before.
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So here's a question for you. What's the name of the country immediately to the south of the United States? You know the one which shares a border along the Rio Grande (so right, I'm not talking about Cuba).

I'm talking about Mexico.

What is the actual name of the sovereign state of Mexico?

I'm sure I only know one person who would be able to say off the bat what the answer is, and that's my brother-in-law Dave Lewis.

The actual name (in Spanish) is Estados Unidos Mexicanos

In English the name is United Mexican States.

How could I have possibly not known that?

UPDATE: as per Dave's comment below, my childhood friend Todd (being a high-school Spanish teacher) knew the actual name of Mexico. So that's 2 people.