The Chicago mayoral election of 1887 saw Republican John A. Roche win by a landslide, receiving more than a two-thirds majority of the vote, defeating Socialist Robert S. Nelson by more than 36 points (a margin of victory which was itself greater than Nelson's vote share).
Incumbent Democrat Carter Harrison Sr. had opted to retire as mayor. Harrison had lost the backing of his party. This came amid declining public support for Harrison. Among other reasons, Harrison had lost the Party’s backing were his handling of the Haymarket Riot and his failure to receive the endorsement of the United Labor Party.
The Democratic Party nominated DeWitt Clinton Cregier, who refused their nomination. After this, and despite his declared intent to retire, they attempted to nominate Harrison, who also refused their nomination.