Among notable historical events in the diocese is the first African-American Episcopal congregations in the South, St. James' Church, at Lafayette Square, in west Baltimore.

He was the first elected primate of the Episcopal Church; for his predecessors, the senior member of the House of Bishops, automatically assumed the position.

Then in 1895, the District of Columbia and adjacent (and increasingly suburban) Montgomery and Prince George's, along with southern Maryland's Charles and St. Mary's counties became the Diocese of Washington.

[2] On March 29, 2008, Eugene Taylor Sutton was elected as the 14th bishop of the diocese;[3] the first African-American to serve in that capacity was consecrated June 28, 2008.

[7] This was followed by the Presiding Bishop, Katharine Jefferts Schori, placing formal restrictions on Cook preventing her from presenting herself as an ordained minister of the Episcopal Church.

The arms of the diocese were designed by Pierre de Chaignon la Rose and were officially adopted at the 133rd diocesan convention in 1916.