Besides having American textbooks, Webster believed that having an Americanized version of English was the first step to truly asserting independence as a nation. "Now is the time and this the country in which we may expect success in attempting changes to language, science and government. Let us then seize the present moment and establish a national language as well as a national government," wrote Webster. His 1806 dictionary was the first American dictionary but his 1828 version, which completely changed how dictionaries were formatted, is his most lasting work. You can browse the 1828 dictionary's entries online.