Here in Kansas, a felony conviction will lead to a temporary loss of the right to vote. But Kansas law automatically restores voting rights to persons with felony convictions once they have completed the terms of the sentence (including any supervision). Under K.S.A. 21-6613, a person with a felony conviction gets the restoration of their right to vote, to hold public office, and to serve on a jury once they complete the terms of their sentence.
So it is across the state line in Missouri. Under Mo. Ann. Stat. §§ 115.133(2) & 561.026(1), a person convicted of a felony is generally unable to vote until they are finished with any term of incarceration or probation or parole. But after the terms of the sentence are completed, the right to vote is restored.
This is something to keep in mind when advising clients about the collateral consequences of any felony conviction in federal court. You should advise clients that they will lose their right to vote (and to hold public office and to serve on a jury) with their conviction. But this loss of civil liberties is usually temporary. Once the client finishes the terms of their sentence they will again be eligible to vote if they live in Kansas or Missouri (or in many other states).