Luigi's Mansion and Fire Emblem are a great one-two punch for this half of the year, but I'm inclined to believe that increasing hype for Pokemon X/Y is at least one of the biggest factors. Just based on personal experience.

It's called Luigi's Mansion: Dark Moon in America ya foo!
But yeah these sales are well deserved! I was skeptical of LM at first, well I'm always skeptical hehe, but more so here as I never even finished the original. Heard lot's of good things about the game, and then when I heard about it's cooperative online modes the deal was sealed, and I don't regret it at all! :D
Now if they could just patch up the online, then it'd be perfect. :)

3DS has many high-quality games, I am surprised it's not selling a lot more on the US. However, it is still beating all other consoles, with the PS3 trying to keep up. That is an amazing accomplishment, i just need to find a cheap, used 3DS to start playing as well some of these games too.

Can't say for sure, but most of the Pokemon fans I know were aware of X/Y shortly after its reveal. However, I may simply live in an area with an unusually high concentration of Pokemon fans.

Luigi's mansion might not be the only reason, I bought a 3DS recently after the announcement of the new Pokemon game

I find it hard to believe people ran out an bought a 3DS after the Pocket Monster X/Y announcement. It was already a given that the 3DS would see more versions of Pocket Monsters, and buying a 3DS now for the games does you no good as they wont be out until the end of the year. But I guess people have done plenty more nonsensical things. :P

Nobody is saying that is the sole cause for the increase in 3DS sales. I'm inclined to believe that some of those who were waiting for Pokemon have become interested in other releases (particularly Luigi's Mansion) and may have decided to purchase the system earlier than planned.

Guess I misinterpreted then my bads. D:

Heh, I actually just bought Luigi's Mansion for the free download of Mario 3D Land, which is the far superior game. And I promptly sold it back once I got Mario. Luigi's is ok, but kinda moves at a slow pace, and too puzzle heavy for my tastes.

In the uk we have pokemon mystery dungeon this week and donkey kong the week after, then three weeks after that is animal crossing so there is a slew of games coming out over the next 6 weeks that will help push hardware, especially animal crossing. I have already bought and finished luigis mansion 2, great game by the way as well as had fire emblem and lego city bought as birthday presents. Have literally just finished lego city half an hour ago and enjoyed that as well. Plus i got monster hunter on the buy 3 get 1 free promo they were running. So many games this year to come with the above games plus mario and luigi, mario golf, mario party, pokemon, yoshis island and zelda. I would be shocked if the 3ds was not close to 45m by the end of this calender year.