Frederick Hager and Robert Hager of St. Paul opened the InterOcean Hotel across Main Street from the new Northern Pacific Railway depot. The Hager brothers had prospered through real-estate speculation and the lumber business.
While observing the March 1881 flood through binoculars from the bluffs east of the Missouri River, Frederick saw an opportunity. He took a train to St. Paul, visited the Northern Pacific Railway Land Office, and purchased half the lots in western Mandan. Frederick returned with railcars of lumber and his brothers Robert and Joseph, who joined him in the lumber business on West Main Street. The brothers bought properties for slightly more than $60 per lot and, after Northern Pacific located its passenger depot nearby, resold them within two years for $500 to $1,500 each.
Their hotel stood at the northwest corner of Dilworth Avenue—now Third Avenue Northwest—and Main Street. Built and furnished for $86,000 (about $2,869,000 in 2025 dollars), it was Mandan's first three-story building and opened in April 1882. Art Kredler was its first manager and remained in the position until failing health forced his resignation in February 1926.
The magnificent three-story brick hotel stood directly opposite the new $12,000 (about $400,000 in 2025 dollars) Northern Pacific passenger depot. Its opening coincided with completion of the railroad bridge across the Missouri River. The Hagers encouraged other investors to join Mandan's boom. Marion A. Vinton of New York and Tilden R. Selmes of St. Paul helped finance brick stores along West Main Street.
“The hotel is fitted up throughout in most exquisite taste and is absolutely perfect and complete in all its details. The management which has revolved upon Mr. John Hager has been fully in keeping with the house superlatively first class and the happy combination has made the ‘The Inter-Ocean’ the most powerful advertising medium of Mandan.”
—Advertisement in the Daily Pioneer, “Immigrant Edition No. 2,” 1883
Among the hotel's most notable features was indoor plumbing, then uncommon in Dakota hotels. It also had central steam heat supplied by an Osborne patented apparatus installed for $12,000 (about $400,000 in 2025 dollars). Each guest could regulate the radiator in their room. The hotel's furnishings were compared with those in New York's finest hotels, and the management took pride in advertising a dining-room staff of “colored” waiters.
In 1883, a local newspaper reported that prominent guests including Henry Villard, Rufus Hatch, and Sir John Rose had called it the finest and most complete hotel west of Chicago. Sitting Bull attended a musical play there.
In 1896, the hotel moved its dining room to the former east parlor on the second floor, while the kitchen and pantries remained on the first. A new dumbwaiter carried meals upstairs.
R. B. Hanna purchased the property in 1916 and renamed it the Lewis and Clark Hotel. The building was demolished the following year. A new Lewis and Clark Hotel, which remains standing, opened on the site in January 1918.