The Atlantic monthly

subtitled ‘a magazine of literature, art and politics’, this was one of the most prestigious American monthly magazines from its inception in November 1857. It was published in Boston, the acknowledged cultural capital of the United States in the nineteenth century, by Phillips, Sampson & Co., and later by an independent Atlantic Monthly Co. The editors in the period covered by James’s working life were:
James Thomas Fields (1817-1881) editor 1861-1871,
William Dean Howells (1837-1920) assistant 1866-1871, editor 1871-1881,
Thomas Bailey Aldrich (1836-1907) editor 1881-1890,
Horace Elisha Scudder (1838-1902) editor 1890-1898
and ...

the magazine published James’ work, both fiction and non-fiction, regularly (when I get time I might offer you a list, but until then you’ll have to consult the Edel and Laurence Bibliography, sorry!