The Ladies' Agreement of 1921 was an informal agreement between the United States and Japan that barred the emigration of picture brides. This agreement almost completely ended Japanese emigration to America, following the Gentlemen's Agreement of 1907. The previous arrangement allowed the wives and family members of Japanese currently living in the United States to emigrate from Japan, but the Ladies' Agreement closed this loophole for prospective immigrants.
References
Ladies' Agreement Wikipedia(Text) CC BY-SA