do the place-names of Arkansas and Kansas have different origins?

Question

or are the different pronunciations of the two just down to local accent?

Answer 1

Officially? Yes. Speculatively? Maybe same origin.
_The World Almanac_ offers the following.
"Arkansas--Algonquin name for the Quapaw Indians, meaning 'south wind.'"
"Kansas--Sioux word for 'south wind people.'"
Wikipedia contributes further information. "Arkansas" may be a French transcription of an Illinois Indian word. "Kansas" originates with the French "River of the Cansez" on maps. The French "Cansez" referred to the Kansa Indians.
Please note that Algonquin and Siouan (incl. Sioux) languages are separate language families. Therefore, "Arkansas" and "Kansas" have different origins officially.
However, I am intrigued that "south wind" indicated both /ar-kan-sa/ and "Kansa" for two groups living in proximity. Many Algonquin and Sioux people lived near each other.
Furthermore, I am intrigued--as you are--about the different pronunciations. Why would Americans know to maintain the silent s in "Arkansas"? Perhaps one generation taught the next simply. Why would Americans know then that "Kansas" had a sounded s? Perhaps "Cansez" taught them. Perhaps people wish to differentiate and, thus, promote unique communal identity. For example, "Nevada" w/ a schwa is the state, but "Nevada" w/ a long-a is an Iowa town. "Missouri" ends in long-e (phonetically) except around and in Missouri where the last i becomes short-a. And, of course, "educated" Missourians say long-e while sipping "sodas" and nibbling "chocolates" while the rest of us relish "pop" (ubiquitously called "Coke") and pogie-bait. Berlin, Germany stresses its second syllable in English, but Berlin, Wisconsin, stresses its first. Carmel in California has two syllables, but Carmel in Indiana has approximately one: "Carm'l"

Answer 2

You can, but it would be against standard terminology and would confuse people and they would make fun of you. Both states had "civilizations" of native people when the Europeans arrived. These tribes changed over time from early discovery to early settlement due to wars or disease or migration or evolvement or whatever. In Arkansas and presumably in Kansas the territories were named by them according to some Indian tribes' names who lived there at some time. Those in Arkansas were not the same as those in Kansas, nor do the present borders of the states correspond exactly to any tribal nations' borders. Also due to dialect or lack of literacy or by the early explorers or the names the map makers put on the maps and also because the Indians had no written language, the names are not exact replicas of the Indian names.

Answer 3

No, not really. BUT they did come into English by different channels. Or, to put it another way, blame it on th 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 on 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 4

Nah ... a bunch of really confused land-locked pirates jumped the border and drew a line in the sand!
Arrrr!

Answer 5

Ar- can- saw

Can - sus