New Mexico, Colorado, Kansas, Missouri, Arkansas and Texas.
the answer is: Oklahoma
Mississippi is bordered by Tennessee, Arkansas and Alabama.
Louisiana is bordered by Arkansas to the north, Mississippi to the east, Texas to the west, and the Gulf of Mexico to the south.
Arkansas
The four states that border Texas are Louisiana, New Mexico, Arkansas, and Oklahoma. Louisiana is to the direct right, Oklahoma is above, New Mexico is directly to the left, and Arkansas only touches a tiny bit in the upper right corner.
Arkansas-13 Texas-21
Texas
The city on the Texas-Arkansas border is Texarkana. It is unique as it is split between two states, with one half in Texas and the other in Arkansas.
Colorado is the width of the Okklahoma Panhandle away from Texas while Texas and Arkansas share a common border.
Arkansas borders directly on Texas. Colorado is separated by the Oklahoma panhandle, so Arkansas is closer, Colorado is further.
Both Missouri and Tennessee are bordered by 8 states. However, Tennessee is separated from Missouri and Arkansas by the Mississippi River. Tennessee does not "touch" Missouri or Arkansas. Therefore, Tennessee "touches" 6 states. Missouri does not "touch" Tennessee. Therefore, Missouri "touches" 7 states. Missouri touches 7 states and Tennessee touches 6 states.