A Sikh girl in Detroit, Michigan celebrates Vaisakhi (also known as Baisakhi) at Wayne State University. More photos of that celebration is available at the Wayne State University flickr feed.
Vaisakhi is the most celebrated event on the Sikh calendar and takes place each April:
Vaisakhi (Punjabi: ਵੈਸਾਖੀ or ਵਸਾਖੀ, vaisĝkhī, is, as well, known as Baisakhi), it is a very important day for Sikhs and one of the most colourful events in the Sikh calendar. It occurs during mid-April every year and traditionally concurs in Punjab with the first harvesting of the crops for the year. So, historically, it has been a very joyous occasion and a time for celebration. However, since 1699, it had marked the very significant religious event of the creation of the Khalsa.
It was during this time in 1699 that Guru Gobind Singh dramatically created the Khalsa order in which Sikhs took on the formal characteristics that we know today. Across the United States, Sikhs will celebrate Vaisakhi by holding a Nagar Kirtan, a religious procession through their community.