Yes, you can marry a U.S. citizen while on a tourist visa and apply for a green card through adjustment of status. However, you must not have entered the U.S. with the intention to marry and stay permanently, as that could be seen as visa fraud.

Marrying a U.S. citizen while on a tourist visa allows you to apply for adjustment of status (Form I-485) without leaving the U.S. The key legal issue is your intent when entering the country. If you entered solely as a tourist and later decided to marry, adjustment of status is generally allowed. However, if you planned to marry from the start, this could violate immigration rules and affect your application.