Why are "Kansas" and "Arkansas" pronounced so different from each other?

Question

Do you know what's the specific reason? That one bugged me since I started learning the English language.

Answer 1

Simple answer -- blame it on the French!

"Arkansas" was a French name for a river, created by adding "Arc" to the French version of the name of an Indian tribe in the region.
http://www.straightdope.com/mailbag/markansa.html

The French dominated the lower Mississippi in the years preceding the Louisiana Purchase, and their influence continued not only in Louisiana but in nearby Arkansas. This included French place names and retaining the French pronunciation of the river (and so the state).
http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=2383
http://www.arkansasheritage.org/people_stories/europeanamericans/french.asp

The territory of "Kansas" --based the same French from Indian name-- did not have the same sort of French influence. When it was settled years later by Americans, the name was quickly Anglicized to the form we know today. (Kansans also pronounce the RIVER name as "Ar-KAN-zus".)
http://www.cimarronkansas.net/arkansas.htm

Arkansas, on the other hand, was determined that the pronunciation of their state name would NOT be changed, and even passed a law to that effect!
http://www.stateline.org/live/ViewPage.action?siteNodeId=136&languageId=1&contentId=15538

Answer 2

The name Arkansas is taken from the Arkansas River, which is named for the Native Americans of the Arkansa tribe. The s was added as a plural, though it remains silent in the pronunciation formally adopted by the state’s legislature.

Answer 3

Kansas was mispelled from the original Indian tribe name of Kanza. Thus, Kansas is as it as spelled. In the city of of Wichita specifically, the river running through it is not Arkansas as the state but Ar-Kanzas.

Answer 4

I agree with the above post. Additionally, Arkansas is often pronounced the same as Kansas, regionally.

Answer 5

most likely some obliteration and transliteration of the original native american