“Eureka!” is the official motto of which US state?

Most of the United States' 50 states have a state motto, as do the District of Columbia, and 3 U.S. territories. State mottos can sometimes be found on state seals or state flags. Some states have officially designated a state motto by an act of the state legislature, whereas other states have the motto only as an element of their seals.

California’s state motto “Eureka!” is Greek for “I have found it!” It may be history’s most famous phrase associated with a bathtub.

The story goes that the Greek mathematician Archimedes exclaimed it after he figured out how to test the purity of gold when he got into his bath and the water overflowed.

The mathematician realized that his body had displaced the water, and, knowing that inferior metals were lighter than gold, he realized he could test the composition of metals by placing them in water and seeing how much fluid they displaced.

The word has appeared on California’s state seal since 1849 and is probably alludes to the discovery of gold, and subsequent gold rush from 1848-1855, after gold was found by James W. Marshall at Sutter's Mill in Coloma, California.

News of the find brought approximately 300,000 people to California, from the rest of the United States and abroad. The sudden influx of gold reinvigorated the American economy, and the sudden population increase allowed California to grow rapidly to statehood.

“Eureka” became the California state motto in 1963, despite attempts to use “In God We Trust” instead.