Delaware Geography

Delaware is the second-smallest state in the United States after Rhode Island.

Delaware is bounded to the north by Pennsylvania, to the east by the Delaware River, Delaware Bay, New Jersey and the Atlantic Ocean and to the west and south by Maryland. Small portions of Delaware are also situated on the far, or eastern, side of the Delaware River Estuary, and these small parcels share land boundaries with New Jersey.

The state of Delaware, together with the Eastern Shore counties of Maryland and two counties of Virginia, form the Delmarva Peninsula, a geographical unit stretching far down the Mid-Atlantic Coast.

The definition of the northern boundary of the state is highly unusual. Most of the boundary between Delaware and Pennsylvania is defined by an arc extending 12 miles (19 km) from the cupola of the courthouse in New Castle, and is referred to as the Twelve-Mile Circle. This is the only true-arc political boundary in the United States. This border extends all of the way to the low-tide mark on the New Jersey shore, which continues down the shoreline until it again reaches the twelve-mile arc in the south; then the boundary continues in a more conventional way in the middle of the main channel (thalweg) of the Delaware River Estuary. A portion of this arc extends into Maryland to the west, and the remaining western border is a tangent to this arc that runs a bit to the east. The Wedge of land between the arc and the Maryland border was claimed by both Delaware and Pennsylvania until 1921, when Delaware's claim was confirmed.

Delaware is subdivided into three counties: from north to south, New Castle, Kent County and Sussex.See also: List of counties in Delaware

Delaware is on a level plain, the highest elevation, located at Ebright Azimuth, near Concord High School, Wilmington; does not even rise 450 feet above sea level. The northern part is associated with the Appalachian Piedmont and is full of hills with rolling surfaces. South of Newark and Wilmington, the state follows the Atlantic Coastal Plain with flat, sandy, and, in some parts, swampy ground. A ridge about 75 to 80 feet in altitude extends along the western boundary of the state and is the drainage divide between the two major water bodies of the Delaware River and several streams falling into Chesapeake Bay in the west.

Since almost all of Delaware is a part of the Atlantic Coastal Plain, the climate is moderated by the effects of the ocean.The state is somewhat of a transistional zone between a humid subtropical climate and a continental climate. Despite its small size (roughly 100 miles from its northernmost to southernmost points), there is significant variation in mean temperature and amount of snowfall between Sussex County and New Castle County. The southern portion of the State has a somewhat milder climate and a longer growing season than the northern portion of the State. Furthermore, the transitional climate of Delaware supports a surprising variety of vegetation. At Trap Pond State Park in Sussex County, bald cypress grow--this is thought to be one of the northernmost stands of these trees. The vegetation in New Castle County, on the other hand, is more typical of that of the northeastern United States. All parts of Delaware have relatively hot, humid summers. While Sussex and Kent Counties are considered to fall in the humid subtropical climate zone, there is some debate about whether northern New Castle County falls in the humid subtropical climate zone or warm continental climate.

Map of Delaware