A chess player is awarded the title of Grandmaster (GM) after performing well over a series
of international tournaments with other Grandmasters. This is measured by
obtaining GM norms. Normally 3 or 4 norms are needed for the title,
depending on the length and type of each tournament. In order to obtain a GM norm a player
must play at least 3 Grandmasters and have a performance of over 2600 FIDE
(international chess rating) in a tournament of at least 9 rounds with players
from at least 4 different countries. Actually the real rules are much more
complicated, but basically they say the same things with a few caveats.
To put things in perspective, there are about 800 Grandmasters in the world and 50 in the United States, of which only about 15 are American born.