Simplify the following text for a Grade 10 native English-speaking person.
Original: In 1986 , the title became a secondary championship in Mid-Atlantic Championship Wrestling when Jim Crockett Promotions gained control of the NWA World Heavyweight Championship .
Simplified: The title remained the primary championship within the Mid-Atlantic territory until 1986 when Crockett gained control of the NWA World Heavyweight Championship . The U.S. Title then became the secondary championship of the promotion .