Moved to Bellingham, Washington

In 1931, Agnes went to Bellingham, Washington,
to help her older sister, who was pregnant.

[...] she left Canada in 1931 for Bellingham in Washington State, joining her sister Mirabel there, despite what she recalled as a terrible relationship with an intellectually inferior sibling. There are unanswered questions about the momentous relocation, including why Martin began high school again in Washington State, graduating at twenty-one; whom she stayed with during these years; and, most perplexingly, what really impelled her to leave home in the first place. 

—Nancy Princenthal on the book Agnes Martin: Her Life and Art

[...] when she was nineteen, she left Vancouver for Bellingham, Washington, to take care of her sister, Maribel, now married, who had become ill during a difficult pregnancy. "I never went back," she says. "As soon as I came, I found out you could work your way through college in America."

—Benita Eisler, on her 1993 New Yorker profile of Agnes Martin