The State of the Union Address (SOTU) is the only Presidential address required by the Constitution. Such and address is included in Article II Section 3, Duties to Congress:
He shall from time to time give to the Congress Information of the State of the Union, and recommend to their Consideration such Measures as he shall judge necessary and expedient; he may, on extraordinary Occasions, convene both Houses, or either of them, and in Case of Disagreement between them, with Respect to the Time of Adjournment, he may adjourn them to such Time as he shall think proper; he shall receive Ambassadors and other public Ministers; he shall take Care that the Laws be faithfully executed, and shall Commission all the Officers of the United States.
Since the first President this has been an annual address or written report. George Washington elected to give an annual address. Thomas Jefferson changed to a written report to avoid echoes of monarchism. Woodrow Wilson returned to the Address to a Joint Session of Congress but the practice did not become the norm until the Reagan presidency. Some presidents between Wilson and Reagan submitted both addresses and written reports.
Lyndon Johnson delivered the first nationally televised State of the Union Address and was accordingly to the first president to address the speech to the entire nation rather than simply the Congress: "Mr. Speaker, Mr. President, Members of the Congress, my fellow Americans" (January 4, 1965).
Texts
Clinton, William Jefferson. State of the Union, 1999.
Obama, Barack. State of the Union 2015.
Washington, George. First Annual Address to Congress on the State of the Union.
References
Barabas, Jason. Presidential policy initiatives: How the public learns about State of the Union proposals from the mass media. Presidential Studies Quarterly 38 (2008): 195–222. [https://doi.org/10.1111/j.1741-5705.2008.02636.x]
Hoffman, D. R. & Howard, A. D. Addressing the State of the Union: The Evolution and Impact of the President's Big Speech. Boulder, CO: Lynne Rienner Publishers, 2006.
Jamieson, Kathleen Hall. "Antecedent Genre as Rhetorical Constraint." Quarterly Journal of Speech 61 (1975) 406-415.
Panagopoulos, C. "Polls and elections: Firing back: Out-party responses to presidential State of the Union Address: 1966-2006." Presidential Studies Quarterly 41 (2011): 604-617.
Pluta, Anne C. "Reassessing the Assumptions behind the Evolution of Popular Presidential Communication." //Presidential Studies Quarterly 45/1 (2015): 70-90. [https://doi.org/10.1111/psq.12171]
Teten, R. L. "Evolution of the modern rhetorical presidency: Presidential presentation and development of the State of the Union Address." Presidential Studies Quarterly 33 (2003): 333-346.
External Links
Annual Messages to Congress on the State of the Union (Washington 1790 - Trump 2019). American Presidency Project.
George Washington, First Annual Message to Congress. Mount Vernon