Cavalier County's history begins with the Verendrye expedition passing through in November 1738 and camping northwest of Olga, followed by an early 1830s fur trading post in Beaulieu and an 1848 battle west of Olga near the O'Brien coulee between Chippewa of Turtle Mountain and Sioux. Surveyed land opened to Homestead entry on January 1, 1863, and in 1873 the county was created from western Pembina County and named by the Territorial Legislature for Charles Cavileer, a saddle maker, fur trader, customs agent, and postmaster from St. Paul who had brought settlers to Pembina County in 1851, though the county's spelling remained Cavalier for unknown reasons. Immigration increased in 1883, when the first school opened in Olga in Father Cyrille St. Pierre's log house on his squatter's claim, beginning with 20 pupils and classes taught in French before a tent was added. Langdon was named in the winter of 1884 for railroad official Robert Bruce Langdon of the Great Northern Railroad, and residents petitioned that year to organize the county, after which the first courthouse was built. A one-room school opened in Langdon in 1886, and in 1887 Langdon won a contested county seat vote over Olga, Rosa Lake, and Lemon despite allegations of fraudulent voting. Blizzard disasters struck in January 1888, in February 1890, in March 1941, in April 1956, and in April 1997, while local government and services expanded with the Langdon Police Department in 1888, city hall, fire department, and jail in 1889, the Langdon Volunteer Fire Department in 1890, electric lights in the 1890s, a library in 1897, telephone service in 1899, a water system in 1917, and rural water service beginning in 1988 and extended to Langdon in 2017. Transportation and communications advanced with Hannah's first telegraph and passenger train in 1897, Langdon's first automobile in 1903, the Langdon Experiment Station in 1907, the first county fair in 1909, an aeroplane exhibition and crash without injuries at the fair in 1911, and the first fiber optic cables to a Langdon house in 2007, while daily railroad service to Langdon ended in 1959 and dial-up Internet arrived in 1995. Disasters and change also marked the county, including a 1909 cyclone in Langdon that killed five and injured 15, the 1912 destruction by fire of Dresden's business district, the 1917 Sarles School fire, a 1948 tornado striking Langdon's two airports, the 2004 burning of the historic Boyd Block building, the 2018 fire that destroyed the 115-year-old Boyd Square building, and the temporary closure of schools and businesses during the COVID-19 pandemic in 2020. Civic and social development included the first hospital in 1910, American Legion posts in 1919-1920, 52 schools recorded in 1927, the organization of Cavalier Rural Electric Co-op in 1945 with its first energized line in 1948, the Sarles swimming pool in 1953, the Northern Lights Arts Council in 1980, Langdon School's renaming to Langdon Area Schools in 2001, and a long record of state championships won by Cavalier County schools from 1912 through 2021.