qualify?

I got in the mail this weekend a letter from the Clydesdales of America... or some goofy name like that.  Anyways, they said I qualified for some Clydesdale National Championship race in Chicago in a few weeks.  Weird.  I wonder what I did to qualify?  I'm guessing if you signed up and finished you qualified... because I have a hard time believing my finishing time had any factor what-so-ever.