Webster had been a workaholic. In the month before his death, he had completed his book A Collection of Papers on Political, Literary, and Moral Subjects. His daughter was at hand when he died and, as she wrote to her husband: "All is over. Father, dear father, has gone to rest... He said his work was done, and he was ready." He was 85 years old.
After his death, his final work was published: a revised version of his An American Dictionary of the English Language (originally published in 1828). Earlier, in his preface to one of the spellers, Webster wrote:
In the progress of society and improvement, some gradual changes must be expected in a living language; and corresponding alterations in elementary books of instruction, become indispensable: but it is desirable that these alterations should be as few as possible, for they occasion uncertainty and inconvenience. And although perfect uniformity in speaking, is not probably attainable in any living language, yet it is to be wished, that the youth of our country may be, as little as possible, perplexed with various differing systems and standards. Whatever may be the difference of opinion, among individuals, respecting a few particular words, or the particular arrangement of a few classes of words, the general interest of education requires, that a disposition to multiply books and systems for teaching the language of the country, should not be indulged to an unlimited extent. On this disposition however, the public sentiment alone can impose restraint.
*Information in this post comes mostly from Joshua Kendall's recently-released biography The Forgotten Founding Father: Noah Webster's Obsession and the Creation of an American Culture.