You’re probably thinking of Wyoming. Wikipedia: The first state to grant women the right to vote had been Wyoming,[6] in 1869, followed by Utah[7] in 1870, Colorado in 1893, Idaho in 1896, Washington[8] in 1910, California[9] in 1911, Oregon[10] and Arizona[11] in 1912, Montana in 1914, North Dakota, New York,[12] and Rhode Island[13] in 1917, Louisiana,[14] Oklahoma,[15] and Michigan[16] in 1918.[17]
You’re probably thinking of Wyoming. Wikipedia: The first state to grant women the right to vote had been Wyoming,[6] in 1869, followed by Utah[7] in 1870, Colorado in 1893, Idaho in 1896, Washington[8] in 1910, California[9] in 1911, Oregon[10] and Arizona[11] in 1912, Montana in 1914, North Dakota, New York,[12] and Rhode Island[13] in 1917, Louisiana,[14] Oklahoma,[15] and Michigan[16] in 1918.[17]
Nationwide in the US, it was 1920.