All economic activity involves some degree of physical risk. Credible data on work injuries and fatalities among our agrarian ancestors are difficult to come by. Yet agricultural work must have been quite unappealing, considering that so many people in the early 19th century preferred factory work over farm work.

Even today, notes the U.S. Department of Labor, agriculture “ranks among the most dangerous industries.” In 2011, the “fatality rate for agricultural workers was 7 times higher than the fatality rate for all workers in private industry; agricultural workers had a fatality rate of 24.9 deaths per 100,000, while the fatality rate for all workers was 3.5.” Likewise, the Workplace Safety and Health (WSH) Institute in Singapore found that global fatality rates per 100,000 employees in agriculture ranged from 7.8 deaths in high-income countries to 27.5 deaths in the Southeast Asia and Western Pacific regions in 2014. Manufacturing deaths ranged from 3.8 in high-income countries to 21.1 in Africa.

By modern standards, working conditions in mines and factories during the first 100 years of the Industrial Revolution were appalling. As U.S. President Benjamin Harrison put it in 1892, “American workmen are subjected to peril of life and limb as great as a soldier in time of war.” In the United States, estimates Harvard University psychologist Steven Pinker, 61 per 100,000 workers died in work- related accidents as late as 1913. That number fell to 3.2 in 2015. That’s a 95 percent reduction. A similarly encouraging trend applies globally. According to the WSH Institute estimates, 16.4 workers per 100,000 employees died worldwide in 1998. By 2014 that number fell to 11.3. That’s a 31 percent reduction over a remarkably short period of 16 years. Put differently, workplace fatalities seem to be falling by almost 2 percentage points each year.

What accounts for those improvements? Labor union activism, including strikes and protests, has been traditionally credited with making the workplace safer. The massive economic expansion in the second half of the 19th century also tightened the labor market, empowering workers to gravitate toward more generous employers. Only after a critical mass of workers achieved more tolerable working conditions did more general workplace regulations become imaginable and, more importantly, economically sustainable.