Maryland's Western Shore (not to be confused with Western Maryland) is an area of Maryland west of the Chesapeake Bay. Originally, it included all areas not on the Eastern Shore and some colonial and later state government functions were administered separately for each region. The term no longer identifies an official region of Maryland and is used in contrast to the "Eastern Shore", which has long had a distinct historical, cultural, sociological, and economic character and sense of personality, well known in American and state history, politics and events, especially before the 1952 construction of the Gov. William Preston Lane Memorial Bridge (Chesapeake Bay Bridge).
Since it is not an officially defined region, there is no official border for the Western Shore. At a minimum, it can be taken to include the tidewater region bordering the Chesapeake Bay on the west. This includes the cities of Baltimore and Annapolis, nearly all of Southern Maryland, much of the Baltimore-Washington Metropolitan Area, and part or all of the following counties:
To residents of the Eastern Shore, the term "Western Shore" still often refers to all of Maryland west of the Chesapeake Bay.
The Environmental Protection Agency (EPA) defines the "Western Shore" as the land from Harford County in the northeast down to Calvert County's bayfront communities to the southeast.
Oxygen levels in the Chesapeake Bay are a continuing concern. As of 2010[update], the EPA is introducing new laws to reduce Western Shore nitrogen pollutants released into the Bay, from 16.89 million lbs per year to 9.74 million lbs per year. The laws would also restrict phosphorus pollutants from 830,000 lbs per year to 460,000 lbs per year.