After the thirteen, new states joined one at a time, each by an act of Congress, as people settled the lands the country added. The last two joined in 1959.
Key idea
Delaware was first (1787) and Hawaii last (1959). Eastern states mostly joined early; many western states joined around 1890 (six in 1889 and 1890 alone); Alaska and Hawaii both joined in 1959.
Why it works
Why didn't the states join neatly from east to west? A territory could ask to become a state when enough people lived there and they wrote a state constitution that Congress accepted. Gold, ports and farmland drew people to some places much earlier than others. The California Gold Rush brought so many people that California joined in 1850, while the dry lands between it and Texas filled in slowly.
Worked example: Years apart
Delaware became a state in 1787 and Hawaii in 1959. How many years apart is that?
- Subtract: 1959 − 1787.
- 1959 − 1787 = 172.
Answer: 172 years.
Common mistake
People think states joined in order from east to west. Texas (1845) and California (1850) joined decades before nearby states such as Nevada (1864), Utah (1896), New Mexico and Arizona (both 1912). Oklahoma came in 1907, and Alaska and Hawaii came last, both in 1959.