North America has 9 territories and the player that holds this region receives an additional 5 reinforcements per turn.
With three points to defend from, North America is easier to defend than Europe for the same amount of additional reinforcements per turn. The more difficult aspect of North America is first conquering it. A large amount of armies must be devoted to conquering it so the player that attempts this must not waste resources attacking in other regions unless absolutely necessary. One major problem that tends to occur is that a player that conquers South America will make it very difficult for anyone else to conquer North America. The ability to hold off a player from conquering South America is sometimes necessary to be able to conquer North America. It is advisable to conquer it if you own five or more territories in the region.