Tā shì quánměi zuì shòu huānyíng de yùndòngyuán zhīyī.
He is one of the most popular athletes in all of America.
Tips
grammar
全 + country abbreviation is a productive pattern: 全美 (all of America), 全英 (all of Britain), 全日 (all of Japan), 全中 (all of China, though 全国 is far more common for China).
