Final answer:
Harper's Magazine, The Atlantic, and National Geographic are three magazines published in the 1800s and early 1900s that are still in circulation today.
Step-by-step explanation:
Three magazines that were published in the 1800s and early 1900s and are still being published today include Harper's Magazine, The Atlantic, and National Geographic. Harper's Magazine, founded in 1850, is the second-oldest continuously published monthly magazine in the U.S. The Atlantic was created in 1857 and has played a significant role in shaping American literature and public policy. National Geographic, recognized for its detailed maps and stunning photography, began its publication in 1888 and is renowned for its exploration of science and culture.