[USDA FEIS] Origins and Introduction: Musk thistle is native to western and central Europe, northwards to Scotland and extending to Sicilia, central Yugoslavia, and Ukraine, western Siberia, Asia Minor, and North Africa. It has since been introduced to North and South America, Australia, and New Zealand. Worldwide distribution of musk thistle is limited to the temperate zones of the northern and southern hemispheres, although occasional sightings in the tropics at high elevation have been reported. The earliest records of musk thistle in North America are from central Pennsylvania in 1852, followed by several records of its occurrence along the east coast in the late 1800s, apparently associated with ship ballast. Musk thistle began to appear in the Midwest around the turn of the 20th century. By the early 1940s, musk thistle was regarded as a potential problem in North America. In 1976, Dunn reported the presence of musk thistle in at least 1 out of every 10 counties in the U.S. As of 1999, musk thistle was reported to occur in 45 states in the U.S. and all of the southern Canadian provinces. (link added by Jessica Johnston)