They are dependent upon wetland habitats and moist woods and are in decline due to loss of habitat. The park is about 800 square miles in area and was established in 1934. It is the most visited park in the entire national park system. Over 10 million people visit annually, many of them driving cars into the park. This factor makes the park vulnerable to pollution with most summer days rating an unhealthy ozone level, and a reduced visibility of twenty miles.
Air pollution is one of the most serious problems facing the park.
Diversity of the Coastal Plain of North Carolina Varieties of plants common to the southeast part of the continent cross with species common to more northern regions. North Carolina has more biodiversity in the southeast coastal plain than many states have altogether. One of the most diverse areas of the state has been the long leaf pine ecosystem. Long leaf pine is the state tree of North Carolina. Long leaf pine forests have slowly been in decline since colonial times.