As I write this, the Wikipedia article for Jedidiah Morse is relatively short, but it is on-target in portraying him as a clergyman, geographer, and scientist, as well as the father of Samuel F. B. Morse, inventor of the telegraph. I am not aware of Morse doing any direct mission work among American Indians, but rather, he held some kind of administrative post in the American Board of Commissioners for Foreign Missions (ABCFM).
As I've said before, for many years there wasn't much separation between church and state when it came to Indian missions. So it shouldn't be too surprising that Rev. Morse also worked as a consultant or advisor to the United States Secretary of War. In 1820, Morse made a tour of many tribes and filed a 496-page report which was printed in 1822 and recently made available online. One of the notable events of Morse's 1820 tour was a sermon preached at Fort Howard (located near the modern city of Green Bay, WI). That sermon has been recognized as the first protestant sermon preached in what is now Wisconsin and it helped pave the way for the New York Indians, many of whom were protestant Christians.
According to Google Images, this map is probably Morse's own work, and he is known as the "father of American Geography." The map is taken from his Report to the Secretary of War.
Morse's report promotes the "civilizing" of American Indians. While you may remember that I once wrote that the "civilizing" process was harmful to Native cultures, I still think that Rev. Morse deserves a certain amount of recognition as an advocate for Indians. Why? Well, it doesn't seem like there was much diversity sensitivity back then. By advocating for "civilizing" the Indians, Morse was way ahead of other white Americans who wanted to exterminate them.
Some, I will hope...that the number is small, have...said, 'Indians are not worth saving. They are perishing - let them perish. The sooner they are gone the better.' ....A sufficient answer to such of these objections.... will be found, I conceive, in the facts collected in the Appendix of this work. It is too late to say that Indians cannot be civilized (page 81).
and he continues on page 82:
Indians are of the same nature and original, and of one blood, with ourselves [white people]; of intellectual powers as strong, and capable of cultivation, as ours. they as well as ourselves, are made to be immortal. To look down upon them, therefore as an inferior race, as untameable, and to profit by their ignorance and weakness; to take their property from them for a small part of its real value, and in other ways to oppress them; is undoubtedly wrong, and highly displeasing to our common Creator, Lawgiver and final Judge.
There were some whose urging of the New York Indians to remove west came across as self-serving, but Morse really had nothing to gain by their leaving. Morse and others - quite possibly this includes many of the Stockbridge and Brothertown Indians - felt that Indians would have a better chance to prosper if they were segregated from whites, particularly from the kind who would sell them alcohol.