President William Howard Taft signed the proclamation admitting Arizona on February 14, 1912, ending a territorial period marked by disputes over water rights, mining interests, and a proposed state constitution that Taft had initially rejected for allowing judicial recall. With Arizona's admission, the continental United States reached its full complement of 48 states, a configuration that held for nearly half a century.
Arizona's road to statehood was bumpier than most. Congress and President Taft balked at the territory's proposed constitution, which included a provision allowing voters to recall judges, a measure Taft considered a dangerous assault on judicial independence. Arizona's leaders grudgingly stripped the clause to get statehood approved, then, in a bit of political theater, reinstated it by popular vote almost immediately after joining the Union.
Taft signed the final proclamation on February 14, 1912, making Arizona the 48th state and the last of the contiguous territories to join. It completed a continental map of the United States that many Americans today picture as fixed and permanent, but which had in fact been assembled piece by piece over more than a century, from the original thirteen colonies to this final desert admission.
The date's overlap with Valentine's Day was pure coincidence, but Arizonans have leaned into it since, sometimes calling their state 'the Valentine State.' The 48-star flag configuration lasted until Alaska and Hawaii joined in 1959, the longest-standing arrangement in American flag history.