Joe Biden overwhelmingly won a Democratic presidential primary in Kansas conducted exclusively by mail balloting by the state party because of the coronavirus pandemic.
The former vice president had been expected to prevail and he captured 77% of Saturday's vote.
Vermont Sen. Bernie Sanders was still in the race when the Kansas party began mailing ballots at the end of March, but he suspended his campaign and endorsed Biden.
The Democratic party says participation more than tripled over four years ago, with 34.7% of registered voters participating.
Party chairwoman Vicki Hiatt says this proves that mail-in voting can be successful.