PORTLAND – The 21st annual “10 x 10” show and sale will be open 5 to 8 p.m. Friday and 10 a.m. to 2 p.m. Saturday at June Fitzpatrick Gallery at Maine College of Art, 522 Congress St.

It’s a seminal spring event in the Portland art community, with lines forming long before the gallery opens. Ten artists show 10 works each, measuring 10 inches by 10 inches on Friday evening. On Saturday, each mounts an additional 10 pieces.

The 10-by-10 format is the only restriction. The content and media are varied and diverse. This year’s artists are Susan Amons, Kate Cheney Chappell, Rebecca Goodale, Lindsay Hancock, Pat Hardy, Colleen Kinsella, Richard Brown Lethem, Gail Page, Sharon Townshend and Michael Walek.

Each piece costs $200 plus tax.

Since its inception more than two decades ago, the 10-by-10 format has been copied many times, but the Portland show is the original. Artists in past shows include many of Maine’s most celebrated: Richard Wilson, Eric Hopkins, Kate Mahoney, Alice Spencer, Natasha Mayers, Abby Shahn, Grace DeGennaro, Denny Ryus, Marjorie Moore, Meg Brown Payson, Nikki Schumann, Brita Holmquist, Chris Ayers, Robert Shetterley, Carol Bass, Josefina Auslender, Mary-Louise Hedstrom and Bill Curtsinger.