Simplify the following text for a Grade 7 native English-speaking person.
Original: It is estimated that in the early 18th century , the Bald Eagle population was 300,000 â `` 500,000 , but by the 1950s there were only 412 nesting pairs in the 48 contiguous states of the US .
Simplified: In the early 1700s , the number of bald eagles were 300,000 â `` 500,000 , but by the 1950s there were only 412 nesting pairs in the United States .