Historical Fiction:
* The Best of All (1933) - A novel set during the French Revolution, focusing on a young woman's life and her relationship with a noble.
* The King's Agent (1937) - A historical mystery set in 17th-century England.
* The Unconquered (1940) - A sweeping epic set in the American West, centering on the struggles of a pioneer family.
* The Wind Blows Free (1941) - A historical romance set during the early years of the American Revolution.
* The Man Who Found Himself (1942) - A novel set during the early days of the automobile industry, following a young man's journey to success.
* The Other Half (1943) - A novel set in the late 19th century, exploring the lives of women in a small town.
* The Long Road West (1947) - A historical novel set during the westward expansion, focusing on a family's experiences on the Oregon Trail.
* The Great Tradition (1949) - A novel set in the early 20th century, exploring the changing role of women in society.
* The Land and the People (1951) - A historical novel about the early days of settlement in California.
* The Edge of the Wilderness (1953) - A novel set in the 1830s, focusing on a family's struggles to survive in the Kentucky wilderness.
Other Works:
* A Mystery in the Woods (1938) - A juvenile mystery novel.
* The Secret of the Treasure Chest (1940) - A juvenile mystery novel.
* The Mystery of the Silver Star (1942) - A juvenile mystery novel.
This is not an exhaustive list, but it provides a good overview of Marion Clyde Day's writing. Her works are often characterized by strong female characters, detailed historical settings, and dramatic plotlines.