McKenzie was born April 3, 1850 in Ontario, Canada, the son of Scottish immigrants. He attended public school in Toronto, but quit school at age 11 to seek his fortune.
At age 16 McKenzie arrived in Dakota Territory in the United States, and while still in his teens he became a scout in the US Army for George Armstrong Custer cavalry. He later worked in railroad construction, at a time when railroads were being extended throughout the Plains. He ran a factory that made carbonated beverages.
McKenzie served as the sheriff of Burleigh County, North Dakota from 1874 to 1886. He was later a deputy U.S. marshal. He became an influential figure in Dakota Territory, and later in the new state of North Dakota, where he personally selected many Republican candidates for the state legislature, the U.S. Senate, and the U.S. House of Representatives. He was the Republican National Committeeman for North Dakota for 21 years.
McKenzie built and ran a powerful political organization in North Dakota. However, the “McKenzie machine” was widely accused of stealing votes, intimidating voters, and physically beating opponents.
In 1900, McKenzie secured the appointment of his hand-picked candidates for the federal judge, federal district attorney, and other government posts in the gold-rush boom town of Nome, Alaska. He then travelled to Nome with the federal law-enforcement apparatus at his command. His obedient judge took some gold mines from their rightful owners, and illegally appointed McKenzie as the receiver to operate the mines while the owners appealed.
While McKenzie mined their gold, the original owners of the gold mines took their case to the Ninth Circuit Court of Appeals in far-away San Francisco. The appeals court reversed the federal judge in Nome, but McKenzie refused to comply with the order of the appeals court, and continued taking gold out of the mines.
The Ninth Circuit Court of Appeals had McKenzie arrested, found him guilty of contempt of court, and sentenced him to one year in jail. McKenzie served three months of his jail sentence before he was pardoned by President William McKinley in May 1901.
North Dakota voted out the McKenzie machine in 1906. McKenzie retired from his position as party national committeeman in 1908.
McKenzie died June 22, 1922 in St. Paul, Minnesota. He had six children from two marriages. McKenzie County, North Dakota was named for him, as were the towns of Alexander, North Dakota and McKenzie, North Dakota.
Rex Beach’s 1906 novel The Spoilers fictionalized McKenzie’s attempted theft of gold mines in Nome. The novel portrayed McKenzie as the fictional character Alexander Macnamara. The novel was made into a stage play, and into five film versions. Randolph Scott played the McKenzie/Macnamara character in the 1942 film. James A. Michener's novel Alaska bases a key fictional character of chapter 9 on McKenzie's Nome dealings .