At the 2000 census , it was delineated as a census - designated place ( CDP ) , with a population of 33,379 .
( St. Charles comprises nearly all the population of Waldorf 's zip code 20602 , and much of 20603 ) .
At the 2000 census , St. Charles was delineated as a census - designated place ( CDP ) , with a population of 33,379 .
( St. Charles comprises nearly all the population of Waldorf 's zip code 20602 , and much of 20603 ) .