Ever since the publication of Henry Thoreau's four posthumous essay collections, bibliographers and biographers have credited Ralph Waldo Emerson, in the case of Excursions (1863), or William Ellery Channing, in the case of The Maine Woods (1864), Cape Cod (1865), and A Yankee in Canada (1866), with either editing the collections or co-editing them with Sophia Thoreau, Henry's younger sister. This essay provides evidence from letters, books, diaries, and articles, as well as from the essay manuscripts themselves, that Sophia Thoreau alone edited her brother's essay collections for publication after his death from tuberculosis in 1862. She alone also chose the editor for her brother's Journal before her death in 1876.