The City of Southeast Seattle was incorporated on July 2, 1906 following the merger of the districts of Hillman City, York, and Southeast Seattle. It was apparently incorporated for the sole purpose of petitioning to be annexed to the City of Seattle.

At the second meeting of the City Council, a petition was filed carrying 128 signatures calling for a vote on annexation. On August 17, 1906, the electorate voted 221-8 to petition the Seattle City Council to annex Southeast Seattle as the City's 12th Ward. In October, the Seattle City Attorney advised the Southeast Seattle Council that it could not be annexed as a separate ward.

In the meantime, a citizen proposal to merge with the City of Columbia, which supplied fire protection services to Southeast Seattle, received no Council action. On December 5, 1906, the electorate voted 181-70 to annex Brighton and to advance to City of the Second Class status.

A second petition to the Seattle City council asked that Southeast Seattle be annexed as part of the second ward because of the "urgent necessity for water, light and adequate transportation facilities." The Southeast Seattle City Council opposed unconditional annexation, but the public supported immediate annexation under almost any terms. Annexation finally came on January 7, 1907.