I started ballroom dancing a year ago and I'm
interested in training on the professional level. What are some of the premier schools for competitive ballroom dance in the US or elsewhere? I'm willing to relocate!

Many U.S. teachers begin their professional training with Arthur Murrays or Fred Astaire. Either of these franchised schools will give you free training, in exchange for something like a 1-year contract. The level of dancing is not highly competitive, but it's a start. Also, it depends on which school you go to... If you find one with a really good teacher, then you're set. Generally, Freds is a bit more into the competitive scene than Murrays, which is almost strictly social.

Since you're willing to relocate, as a serious dancer you might consider the Metronome Ballroom, which is located somewhere in the San Francisco area. I hear they have a phenomenal professional training program.

It also doesn't hurt to get a partner, since you can split the cost of coaching. Also, practicing with a partner will increase your speed of progression considerably.

I hope this helps.

Sincerely,
Jonathan Atkinson