The Chesapeake Bay Bridge (commonly known as the Bay Bridge) is a major dual-span

Twin bridges

Twin bridges are a set of two bridges running parallel to each other. A pair of twin bridges is often referred to collectively as a twin-span or dual-span bridge. Bridges of this type are often created by building a new bridge parallel to an existing one in order to increase the traffic capacity...

 bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

 in the U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

. Spanning the Chesapeake Bay

Chesapeake Bay

The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...

, it connects the state's rural Eastern Shore

Eastern Shore of Maryland

The Eastern Shore of Maryland is a territorial part of the U.S. state of Maryland that lies predominately on the east side of the Chesapeake Bay and consists of nine counties. The origin of term Eastern Shore was derived to distinguish a territorial part of the State of Maryland from the Western...

 region with the more urban Western Shore

Western Shore

Maryland's Western Shore, not to be confused with Western Maryland, is an area of Maryland west of the Chesapeake Bay. The term does not identify an official region of Maryland but it is often used in contrast to "Eastern Shore"...

. The original span opened in 1952 and, at the time, with a length of 4.3 miles (6.9 km), it was the world's longest continuous over-water steel structure. The parallel span was added in 1973. The bridge is officially named the William Preston Lane, Jr.