Okay, first of all there is an area called THE CANYON PASS
THERE ARE NO CANYONS IN PLAINS
second,
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majority =/= small part
If Central America does include Mexico, than the largest country in Central America is Mexico. However, if you do not take Mexico as being part of Central America, then Nicaragua is the largest country in Central America.
Source: Some place called otooo.com
Nicaragua... Lets find out some Nicaragua Geography...