Simplify the following text for a Grade 9 native English-speaking person.
Original: The Ninth International Conference of American States was held in BogotÃ between March and May 1948 and led by United States Secretary of State George Marshall , a meeting which led to a pledge by members to fight communism in America .
Simplified: These countries held the ninth International Conference of American States between March and May 1948 at BogotÃ .