Florida added the twenty-seventh star So the flag of the United States, Texas the twenty-eighth, and Iowa the twenty-ninth. By an act of Congress March 3, 1845, the territories of Florida and Iowa were authorized to enter the Union as states if and when they should meet the requirements for admission to statehood. The joint admission followed a policy designed to maintain a balance of power in Congress upon the serious questions of the times, mainly slavery, by admitting a Northern and a Southern territory together.
Davis, T. Frederick
"Pioneer Florida: Admission to Statehood, 1845,"
Florida Historical Quarterly: Vol. 22:
3, Article 4.
Available at: https://stars.library.ucf.edu/fhq/vol22/iss3/4