The 19th Amendment to the U.S. Constitution, which granted women the right to vote, was passed by Congress on June 4, 1919, and ratified on August 18, 1920. This amendment legally guaranteed American women the right to vote, marking a significant milestone in the history of womens suffrage in the United States. However, its important to note that even after the 19th Amendment, many barriers to suffrage remained, and it would be several decades before all women, particularly women of color, were able to exercise their voting rights. Additionally, before the 19th Amendment was ratified, women had voting rights in various capacities as early as 1838 in some states, such as New Jersey and the Utah Territory.
Therefore, women could vote in the United States starting in 1920 after the ratification of the 19th Amendment to the U.S. Constitution.