The United States N-class submarines were a class of seven coastal defense submarines built for the United States Navy during World War I.

The United States L-class submarines were a class of 11 coastal defense submarines built 1914–1917, and were the most modern and capable submarines available to United States Navy when the country entered World War I. Despite being considered a successful design by the USN, war experience in European waters demonstrated that the boats lacked the range, speed, and endurance to conduct extended patrols in the North Atlantic.