Statue of Seaman at Columbia View Park in St. Helens, Oregon
Seaman, a Newfoundland dog, became famous for being a member of the first American overland expedition from the Mississippi River to the Pacific coast and back. He was the only animal to complete the entire trip. He was purchased for $20 in Pittsburgh, Pennsylvania by Captain Meriwether Lewis while he was in the city awaiting completion of the boats for the voyage in August 1803, for his famed Lewis and Clark expedition.
During the expedition, around May 14, 1805, Captains Meriwether Lewis and William Clark performed surgery on one of Seaman's arteries in his hind leg that had been severed by a beaver bite. In early 1806, as the expedition was beginning the return journey, Seaman was stolen by Indians and Lewis threatened to send three armed men to kill the Indian tribe. Lewis and Clark's Corps of Discovery ate over 200 dogs while traveling the Lewis and Clark Trail, but Lewis' Newfoundland dog Seaman was spared.
The final reference to Seaman in the journals, recorded by Lewis on July 15, 1806, states that "[T]he musquetoes continue to infest us in such manner that we can scarcely exist; for my own part I am confined by them to my bier at least 3/4 of the time. My dog even howls with the torture he experiences from them."
Due to a transcription error in Lewis' journals, the dog was once thought to have been named Scannon. However, during Donald Jackson's 1984 study of Lewis and Clark place-names in Montana, he found that Lewis had named a tributary of the Blackfoot River Seaman’s Creek (now Monture Creek) and concluded that the true name of the dog was "Seaman". 
In her book Lewis and Clark and Me: A Dog's Tale Laurie Myers reports that Lewis and Clark scholar, Jim Holmberg, discovered a book written in 1814 which listed epitaphs, and inscriptions. The book lists an inscription of a dog collar in a museum in Virginia. This has also been reported by Timothy Alden. The inscription reads: "The greatest traveller of my species. My name is SEAMAN, the dog of captain Meriwether Lewis, whom I accompanied to the Pacific ocean through the interior of the continent of North America." Holmberg's research was published in the February 2000 issue of "We Proceeded On", the newsletter of the Lewis and Clark Trail Heritage Foundation.
A monument to Seaman stands in front of the Custom House in Cairo, Illinois. Other monuments and statues that include Seaman can be found in St. Louis, Missouri, St. Charles, Missouri, Jefferson City, Missouri, Lincoln, Nebraska, Fort Atkinson State Historical Park in Fort Calhoun, Nebraska, the Lewis and Clark Interpretive Center in Sioux City, Iowa, Washburn, North Dakota, Overlook Park in Great Falls, Montana, in Fort Clatsop National Memorial in Seaside, Oregon, Cascade Locks Marine Park in Cascade Locks, Oregon and in Columbia View Park in Saint Helens, Oregon. Seaman also has a monument at the Sacagawea Center in Salmon, Idaho.
Seaman in fiction
Seaman has been a character in several novels. In Tall Tails: Cross-Country with Lewis and Clark by Dona Smith, Seaman has a journal and narrates the expedition. In New Found Land by Allan Wolf, Seaman is a main character. In The Captain's Dog by Roland Smith, Seaman is again the narrator, giving his account of the Lewis and Clark expedition. He is also in "Seaman: The Dog Who Explored the West With Lewis and Clark" by Gail Langer Karwoski.
- "Seaman". National Park Service. Retrieved April 21, 2012.
- "Seaman - Lewis' Newfoundland Dog". Lewis and Clark Trail. Retrieved April 21, 2012.
- "Seaman". Public Broadcasting System. Retrieved April 21, 2012.
- "Seaman". Montana Kids. Montana Office of Tourism. Retrieved April 22, 2012.
- Duncan, Dayton. "Answers To Your Questions". Lewis and Clark - The Journey of The Corps of Discovery. pbs.org. Retrieved June 7, 2013.
- Myers, Laurie (2002). Lewis and Clark and Me: A Dog's Tale. New York: Henry Holt and Co. ISBN 0805063684.
- Holmberg, James J. (August 1996). "Monument to a Young Man of Much Merit". We Proceeded On. 22: 4–13.
- "Seaman, the Newfoundland Dog Explorer". Gentle Newfoundland Dogs. Retrieved April 22, 2012.
- "Graveyards of Illinois - Cairo City Cemetery". Graveyards. Retrieved April 21, 2012.
- Smith, Dona (2004). Tall Tails: Cross-Country with Lewis and Clark. New York: Scholastic Paperbacks. ISBN 0439434416.
- Wolf, Allan (2004). New Found Land: Lewis & Clark's Voyage of Discovery. Somerville, MA: Candlewick Press. ISBN 0763621137.