North Dakota is most likely known as "The Peace Garden State" because it partially houses the International Peace Garden, which overlaps the international border between the United States (US) and Canada. Part of the garden is in the US state of North Dakota, while part of it is in the Canadian province of Manitoba. The garden was established in 1932 to commemorate the lasting state of peaceful affairs between these two nations. The state's department of motor vehicles is credited with stimulating the dedication of "The Peace Garden State" as North Dakota's official state nickname, since they placed this slogan on the state's car license plates in 1956. Residents of the state liked the sound of "The Peace Garden State" so much that North Dakota's legislative body designated this the official state nickname one year later, in 1957.
Like most other US states, North Dakota also has some unofficial state nicknames. These include "The Roughrider State," a slogan which pays homage to the Roughriders, a cavalry brigade that fought with Theodore Roosevelt during the Spanish-American War. Many of these riders were ranchers from North Dakota, hence the state's sense of pride in the name and in the brigade itself. Some have lobbied to officially change the state's nickname to "The Roughrider State," but these initiatives have failed.
Another unofficial state nickname for North Dakota is "The Flickertail State." This nickname refers to the flickertail squirrel, or Richardson squirrel, a species prevalent in North Dakota. "The Peace Garden State," however, remains North Dakota's official state nickname, and is perhaps a reflection of the strong pride residents of this state feel in their status as the home of the International Peace Garden.
The International Peace Garden contains at least 150,000 varieties of flowering plants, as well as lakes, hiking trails, and a chapel. The garden also houses a memorial to the 11 September 2001 attacks on the World Trade Center in New York City. This memorial has been constructed from some of the World Trade Center's original girders. The garden also boasts a Peace Tower, which is about 120 feet (36.6 meters) tall and is made from concrete. The garden's Peace Poles, of which there are seven, bear the words "May Peace Prevail" translated into about 28 world languages.