Tobacco has a long history in the United States. Tobacco distribution is measured in the United States using the term, "tobacco outlet density." An estimated 34.3 million people, or 14% of all adults (aged 18 years or older), in the United States smoked cigarettes in 2015. By state, in 2015, smoking prevalence ranged from between 9.1% and 12.8% in Utah to between 23.7% and 27.4% in West Virginia. By region, in 2015, smoking prevalence was highest in the Midwest (18.7%) and South (15.3%) and lowest in the West (12.4%). Men tend to smoke more than women. In 2015, 16.7% of men smoked compared to 13.6% of women. In 2018, 13.7% of U.S. adults were smokers.