Seaham was a parliamentary constituency, in existence between 1918 and 1950, of the House of Commons of the Parliament of the United Kingdom. It elected one Member of Parliament (MP) by the first past the post system of election.

Seaham was created under the Representation of the People Act 1918 for the 1918 general election, comprising northern parts of the abolished South Eastern Division of Durham. The town of Seaham itself was transferred from Houghton-le-Spring.

It was abolished for the 1950 general election under the Representation of the People Act 1948, with the bulk of its area moved into the new constituency of Easington. The expanded Urban District of Seaham Harbour (now incorporating Seaham) was transferred back to Houghton-le-Spring.^[1]

• The Urban District of Seaham Harbour; and
• the Rural District of Easington.^[2]

The history of this constituency, which incorporated a lot of the mining area of the eastern part of County Durham around Seaham, is of strong Labour Party support.

In the so-called "coupon election" of 1918, Major Evan Hayward was issued a Coalition 'coupon'. However, he repudiated the 'coupon' and stood as a Liberal and was elected. At the following general election, in 1922, Sidney Webb, an early socialist and author of the Labour Party's then-new constitution, was returned. Webb was easily re-elected in 1923 and 1924. He was subsequently raised to the peerage; his successor as parliamentary candidate was Ramsay MacDonald, the leader of the Labour Party at the time. At the 1929 general election MacDonald won, and for the second time became Prime Minister presiding over a minority Labour administration.

The economic crisis after 1929 led to a political crisis in mid-1931, and MacDonald failed to secure agreement in cabinet for his proposed cuts in outdoor relief for the unemployed. MacDonald went to see King George V, who persuaded him to form a National Government. In the general election that followed, MacDonald stood in Seaham as National Labour and was comfortably elected, and continued to serve as a Prime Minister of a National Government that was predominantly Conservative-supported.

MacDonald retired as Prime Minister in 1935 but remained in the Cabinet. In the general election of 1935 he was resoundingly defeated at Seaham by Emanuel Shinwell, the Labour Party candidate. Shinwell was re-elected in the Labour landslide at the 1945 election and subsequently served as MP for the successor constituency of Easington until 1970.

• History of parliamentary constituencies and boundaries in Durham