It's important to note every single one of these names have gone through a process called anglicisation. They are from Indigenous words but they are Indigenous words as interpreted by a European. Note that for accessibility I am using the English name of Indigenous language, I prefer to use the Indigenous name.
The Wampanoag word for Mashpee is Mâseepee, the full Ojibwemowin name for Lake Nipissing is Gichi-nibiinsing-zaaga’igan.
Also, Indiana is not a made up word, it is a Latin nominative neuter plural word. It is directly related to India, as in Bharat, the country in South Asia.
Most common language families are Algonquian by far and then Iroquoian. Muscogean and Uto-Aztecan both have 3, Malayo-Polynesian has 1, Caddoan has 1, and Inuit-Yupik-Unangan has 1.
Most out-of-place names are Wyoming and Mississippi.
Alabama: From Muscogee Albaamu, referring to the Alabama people.
Arizona: Disputed, my hypothesis: From O'odham alĭ ṣonak (small spring) via Spanish Arizonac.
Arkansas: From Quapaw akaansa, "south wind people", via French Arcansas, whence the silent <s>, referring to the Quapaw people. Cognate (related) to Kansas.
Alaska: From Aleut alaxsxaq, "towards the land", via Russian Аля́ска alyáska.
Connecticut: From Mohegan-Pequot quinnehtukqut, "at the tidal river", referring to the River Connecticut.
the Dakotas: From Dakota dakȟóta, "ally".
Hawaii: From Hawaiian Hawai'i, "ancestral homeland".
Illinois: From Miami ilenweewa "he speaks the regular way" via French Illinois, referring to the Illinois people.
Kentucky: From an unknown Iroquoian source meaning prairie. Compare Mohawk kentà:ke.
Iowa: From Dakota ayúxbe "sleepy ones" via French Aiouez, referring to the Ioway people, the Báxoje, "Grey Snow People", in their language, Chiwere.
Kansas: From Kaw/Kansa Kaáⁿze, "south wind people", referring to the Kaw/Kansa people. Cognate to Arkansas. Kaw and Quapaw are very closely related languages.
Massachusetts: From Massachussett Muhsachuweesut, "at the big hill", reffering to the Great Blue Hill of the Wampanoag/Wôpanâak.
Michigan: From Ottawa ᒥᔑᑲᒥ mishigami, "giant lake", referring to Lake Michigan.
Minnesota: From Dakota mní šóta, "cloudy water", referring to the River Minnesota.
Mississippi: From Ojibwe ᒥᓯᓰᐱ misiziibi, "great river", referring to the River Mississippi. misi- and michi- are congates from different Anishinaabe dialects.
Missouri: From Miami wimihsoorita via French, "people with dugout canoes", referring to the Missouria/Ñút'achi people.
Nebraska: From Omaha ní btháska meaning flat water, referring to the River Platte, formerly the River Nebraska. Ní is cognate with mní in Minnesota.
New Mexico: From English new "new" and Nahuatl Mēxihco "homeland of the Mēxihcah" via Spanish Nuevo México, applied to the region as the Spanish believed the Indigenous peoples of New Mexico were rich. related to the Mēxihcah and were looking to conquest.
Ohio: From Seneca Ohi:yo', "good river", referring to the River Ohio. the -io is cognate with Ontario.
Oklahoma: From Choctaw okla + homa, "red people"
Tennessee: From Cherokee ᏔᎾᏏ tanasi "water meeting place" referring to a historic Cherokee village.
Texas: From Hasinai Caddo táyshaʔ, "friend", referring to the Caddo peoples, whence Texas' statement motto "friendship".
Utah: From Ute entaw "mountain diggers" via Spanish Yuta, referring to the Ute people.
Wisconsin: From a disputed Algonquian source, either Ojibwe, Miami, or Menominee, all referring to the River Wisconsin, and all via French Ouisconsin.
Wyoming: From Munsee Delaware xwé:wamənk, "at the big river flat", referring to the Wyoming Valley in Pennsylvania.
