California, the US state with a large Vietnamese community, has won a lot of hearts after officially choosing May 15 as the day for ao dai.
Vietnamese American Janet Nguyen and her co-senators Jim Beall and Richard Pan proposed a resolution to honor the Vietnamese traditional dress.
The resolution said that by celebrating the dress, which is an icon of Vietnam, Vietnamese people in California and across the US can contribute to the US's diverse culture.
A statement from the state senate said Nguyen is the first person to don ao dai in office.
Vietnamese-Americans have been holding their Ao Dai Festival every two years. This year's event will be held in San Jose, on May 15.
There are more than 1.7 million people of Vietnamese origin living in the US, and around half of them in California.