Answer by taking a quote from the following article:

Hanson is an American pop rock band from Tulsa, Oklahoma, United States, formed by brothers Isaac (guitar, bass, piano, vocals), Taylor (keyboards, piano, guitar, drums, vocals), and Zac (drums, piano, guitar, vocals). Supporting members include Dimitrius Collins (keyboards, guitar), and Andrew Perusi (bass) who have toured and performed live with the band since 2007. They are best known for the 1997 hit song "MMMBop" from their debut album released through Mercury, Polygram, Middle of Nowhere, which earned three Grammy nominations. Despite the enormous commercial success of Middle of Nowhere, the band suffered from the merger that eliminated their label, Mercury Records .

Middle of Nowhere was released in the US on May 6, 1997, selling 10 million copies worldwide. May 6 was declared 'Hanson Day' in Tulsa by Oklahoma's then-governor Frank Keating. Although 'Hanson Day' was originally intended to be a one-time occurrence, many Hanson fans all over the world still recognize May 6 as Hanson Day every year. Hanson's popularity exploded during the summer of 1997, and Mercury Records released Hanson's first documentary Tulsa, Tokyo, and the Middle of Nowhere and their Christmas album Snowed In in the wake of their success. Hanson also launched MOE (which stood for Middle of Everywhere), a fan club magazine that ran for 12 issues. After numerous unauthorized biographies of each of the brothers were published, Hanson turned to their close friend, Jarrod Gollihare of Admiral Twin, to write their authorized biography. Hanson: The Official Book reached number 9 on the New York Times Best Sellers List (nonfiction) on February 1, 1998. The band was nominated for three Grammy Awards in 1998: Record of the Year, Best New Artist, and Best Pop Performance by a Duo or Group with Vocal. During the summer of 1998, Hanson began a highly successful concert tour, the Albertane Tour. They performed a string of shows throughout stadiums and arenas in the US, targeting young audiences with a playful and energetic style. A live album, titled Live From Albertane, was released the following fall, as well as their second documentary The Road to Albertane.  In response to the demand for their earlier work, Hanson re-released MMMBop as 3 Car Garage, minus four tracks, in May 1998. To date, the tracks from Boomerang have not been re-released. Three tracks from Boomerang ("Boomerang", "More Than Anything", and "Rain (Falling Down)") and two of the remaining tracks from MMMBop ("Incredible" and "Baby (You're So Fine)") were released on the first MOE CD sent to fan club members.  During the Albertane Tour, Hanson wrote and demoed what would later become the songs for their second major studio album, This Time Around. During this time period, Mercury Records, the band's label, had been merged with Island Def Jam. Almost immediately following the changeover in May 2000, Hanson released their second album, This Time Around, but due to lack of promotional funding, sales were low and the label eventually pulled funding for their tour. The band toured through the summer and fall of 2000 on their own funds.

What day was this on
May 6,