Incredible, thank you! Where'd you dig that up from?
I made it in MSPaint for you.
As I expected, some of these are slightly silly. Texas County is TX, presumably to match the postal abbreviation of the state, yet Delaware County gets DL instead of DE and Washington gets WS instead of WA. Carter County is CR instead of CA, presumably to avoid besmirching the citizens of Ardmore with any association with the hated Californians. I also probably would have changed things around to give MC to McClain County since it has a bigger (and growing) population than McCurtain County, probably giving McCurtain MR and Marshall ML.
It doesn't look at all random or silly to me. Actually, it looks rather well planned-out. See below for my detailed analysis of each of the specific ones you pointed out.
I assume Delaware County is DL instead of DE, because DE are the first two letters of Dewey County as well. Instead, they are DL and DW–first and third letters of each.
Likewise Carter County: CA are the first two letters of Caddo County and Canadian County as well. So for all three, they went with the first and third letters instead.
Likewise with Washington County: WA are the first two letters of Wagoner County and Washita County as well. Instead, they are WS, WG, and WT. For Wagoner and Washington, they again went with the first and third letters. For Washita, they used the letter that does not appear in any other W county.
And likewise all of the Mc counties, which all begin with the first two letters. McCurtain and McIntosh get the first and third letters. For McClain, they used the letter that does not appear in any other Mc county.
I think I remember reading somewhere that Kansas's county code system is so orderly that there is only one instance where the county code is not the first two letters of the county name, where doing so would not cause a conflict with another county.
I'm having difficulty parsing what you mean there. Kansas has loads of county codes that aren't the first two letters–Sedgwick included.
I'd appreciate an example or counterexample to illustrate what you're trying to say. Here are the county codes in alphabetical order, if that helps:
AL. Allen AN. Anderson AT. Atchison BA. Barber BT. Barton
BB. Bourbon BR. Brown BU. Butler CS. Chase CQ. Chautauqua
CK. Cherokee CN. Cheyenne CA. Clark CY. Clay CD. Cloud
CF. Coffey CM. Comanche CL. Cowley CR. Crawford DC. Decatur
DK. Dickinson DP. Doniphan DG. Douglas ED. Edwards EK. Elk
EL. Ellis EW. Ellsworth FI. Finney FO. Ford FR. Franklin
GE. Geary GO. Gove GH. Graham GT. Grant GY. Gray
GL. Greeley GW. Greenwood HM. Hamilton HP. Harper HV. Harvey
HS. Haskell HG. Hodgeman JA. Jackson JF. Jefferson JW. Jewell
JO. Johnson KE. Kearney KM. Kingman KW. Kiowa LB. Labette
LE. Lane LV. Leavenworth LC. Lincoln LN. Linn LG. Logan
LY. Lyon MN. Marion MS. Marshall MP. McPherson ME. Meade
MI. Miami MC. Mitchell MG. Montgomery MR. Morris MT. Morton
NM. Nemaha NO. Neosho NS. Ness NT. Norton OS. Osage
OB. Osborne OT. Ottawa PN. Pawnee PL. Phillips PT. Pottawatomie
PR. Pratt RA. Rawlins RN. Reno RP. Republic RC. Rice
RL. Riley RO. Rooks RH. Rush RS. Russell SA. Saline
SC. Scott SG. Sedgwick SW. Seward SN. Shawnee SD. Sheridan
SH. Sherman SM. Smith SF. Stafford ST. Stanton SV. Stevens
SU. Sumner TH. Thomas TR. Trego WB. Wabaunsee WA. Wallace
WS. Washington WH. Wichita WL. Wilson WO. Woodson WY. Wyandotte