Hawaii officially became a part of the United States in two key steps : annexation in 1898 and full statehood in 1959.

Short answer

  • Annexed by the U.S.: July 7, 1898 (Joint Resolution for Annexing the Hawaiian Islands).
  • Became the 50th U.S. state: August 21, 1959 (official statehood proclamation by President Eisenhower).

So, Hawaii first became a U.S. territory in 1898 , and it became part of the U.S. as a state on August 21, 1959.

From kingdom to U.S. territory

Hawaii was originally an independent kingdom before U.S. control. In the late 19th century, U.S. political and economic interests grew, especially around sugar and Pacific strategy.

  • 1893: The Hawaiian monarchy was overthrown.
  • 1898: The United States formally annexed the Hawaiian Islands by a joint resolution of Congress on July 7, 1898 , making Hawaii a U.S. territory.

This annexation is what made Hawaii “part of” the United States in a legal sense, but not yet as a state.

The road to statehood

For decades, Hawaii remained a U.S. territory, not fully equal to the states.

Key moments:

  1. Early statehood efforts: Bills pushing for statehood appeared in Congress in the early 1900s but stalled for years.
  1. World War II impact: Hawaii’s strategic role in World War II and the loyalty shown by its residents helped build support for statehood afterward.
  1. Statehood bill and referendum:
    • March 18, 1959: President Eisenhower signed the Hawaii Admission Act , approving statehood legislation.
 * June 1959: Hawaiian residents voted in a referendum; over **93–94%** supported becoming a state.

These steps set up the final move from territory to full state.

Official statehood in 1959

Hawaii’s status changed from territory to full state on August 21, 1959.

  • On that date, President Dwight D. Eisenhower signed the official proclamation admitting Hawaii as the 50th state of the Union.
  • This is why Hawaii is celebrated as the 50th state , and why Statehood Day in Hawaii marks this 1959 event.

So if someone asks “when did Hawaii become part of the U.S.?” you can answer precisely:

  • As U.S. territory: July 7, 1898 (annexation).
  • As a U.S. state: August 21, 1959 (admission as the 50th state).

TL;DR

  • 1898: Hawaii annexed and becomes U.S. territory.
  • 1959: Hawaii admitted as the 50th U.S. state on August 21, 1959.

Information gathered from public forums or data available on the internet and portrayed here.