An active Federalist, Webster became a pamphleteer for centralized government and wrote his Sketches of American Policy (1785), proposing the adoption of a constitution. The difficulty of copyrighting his works in 13 states led Webster to agitate for many years for a national copyright law; it was passed in 1790. In 1793 he left Hartford to support Washington's administration by editing the New York's first daily newspaper, American Minerva (later the Commercial Advertiser); he was also editor, at various times, of several magazines. Webster also wrote scholarly studies on a great diversity of subjects, including epidemic diseases, mythology, meteors, and the relationship of European and Asian languages.

During most of his later life he lived in New Haven, Conn., and Amherst, Mass., and was a member of the first board of trustees of Amherst College. Deriving his income from his schoolbooks, he devoted most of the rest of his life to compiling dictionaries. After his Compendious Dictionary was published in 1806, he worked on another, the two-volume The American Dictionary of the English Language (1828), which included definitions of 70,000 words, 12,000 of which had not appeared in such a work before—many were unique to American English. Its definitions were excellent, and the dictionary's sales reached 300,000 annually. Webster's foremost achievement, the work helped to standardize American pronunciation. He completed the revision of 1840, and the dictionary, revised many times since, has retained its popularity. See also dictionary.