Why are Kansas and the last two syllables of Arkansas pronounced differently?

Arkansas is orginally an Native American word from the local tribe the Quapaws. 

Arkansas is not the orginal spelling. It was decided shortly after statehood the specific spelling and pronunciation.  The state kept as Arkansaw to honor the Native American heritage. And the spelling to honor the French settlers. 
This post was edited by my2cents at September 20, 2021 6:34 AM MDT