I entered the U.S. on a tourist visa, and I just married a U.S. citizen. Will I be allowed to stay in the U.S.?

Yes, file adjustment of status at your local USCIS (U.S. Citizenship and Immigration Services) office, and you are allowed to stay in the U.S. while the adjustment is pending.

The foreign spouse can adjust status based on the marriage to a U.S. citizen if the marriage was done on a “spur of the moment” basis, which means that the immigrant did not enter the U.S. with the intent to marry but decided AFTER entry to marry.

See also…

K-1 Fiance and K-3 Spouse Visas

Spouse and Fiance(e) of an American Citizen