The northeastern US is the most populous part of the United States. Much of the North Atlantic coast is a continuous stretch of urban and suburban areas. Water and air pollution, particularly related to fossil-fuel based transportation, are major environmental concerns in this densely populated area, as is habitat fragmentation caused by urban sprawl.
From northern spruce-hemlock-pine forests to Appalachian oak and chestnut forests, the Northeast is characterized by trees. Most were cleared for agriculture following European settlement, but later farm abandonment and conservation led to widespread reforestation. Today, 40% of land in the northeast is forested again, but invasive pests and pathogens increase susceptibility of certain trees to massive die-offs.
This ecoregion consists of the coasts and near-shore waters of nine Atlantic states, totalling 12.7 million acres. Extensive salt marshes with brackish rivers host many birds and serve as nurseries for marine species. Dunes, maritime grasslands, coastal plain ponds and pine barrens are other important habitat types dispersed along the coast. Settlement fragments these habitats extensively, with 40% of land developed.
Largest estuary in the United States, fed by over 150 rivers and streams with a watershed extending through six states. Once an incredibly rich fishery famous for shellfish, overfishing and pollution levels since the early 20th century have drastically depleted the health of the bay, although restoration efforts begun in the 1990s show promise. Sea level rise as a result of climate change is already documented.