Drought generally means a period with abnormally low rainfall, which is also known as meteorological drought.⁴ In 1791, this abnormally low rainfall at Montpelier corresponded to the 1790-1794 El Niño, an event from a periodic weather pattern that causes weather extremes like drought and flooding.⁵ When meteorological drought starts to affect crops, preventing them from getting the moisture they need to grow and thrive, it is known as agricultural drought. Most commonly, agricultural drought⁶ is a problem during the growing season, the part of the year where temperatures are above freezing and allow cold-sensitive crops to grow.⁷ At Montpelier in the late 18th century, the average growing season spanned May 1st to October 14th.

The duration of the 1791 drought was unprecedented compared to its growing season. Lasting 85 days of the growing season (and calendar year), the 1791 drought stunted crop growth for more than two months. This damage was compounded by a growing season that started late and ended early, totaling just 148 days (10% shorter than the average growing season). With such a long drought and short season, drought sensitive crops like corn may have lost most of their yield.⁸ As you can see in the graph below, this damage seemingly came out of nowhere after 1790’s plentiful rainfall.

The Madisons recorded only 89 precipitation events in 1791, 25% fewer instances of precipitation compared to 1790’s 122 events. If Montpelier’s average yearly rainfall was roughly 43 inches, as it is today, the crops in 1791 likely had about 11 inches less rain.⁹

The 1791 precipitation events also resulted in poor moisture. The Madisons usually described precipitation during the drought as a “shower” or “small rain” (as shown in the table at right). The Madisons also occasionally noted the small depth that this rain trickled into the soil, which gives another hint to the volume of moisture. For example, the Madisons recorded “a shower at 5 o’clock to wet the ground about an inch" on July 14th, 1791. As most crops require enough water to wet the soil to a depth of roughly 5 to 12 inches every week, wetting “the ground about an inch” was insufficient.¹⁰ Because the only other precipitation within a week of July 14th was “raining which wet the ground about ½ an inch” on July 16th, the week’s weather did not hydrate the crops. As shown by the pages from the journals below, which include some of the corresponding days in June and July across 1790 and 1791, 1791’s precipitation events did not result in as much moisture as 1790.

Both the Madisons and their enslaved laborers suffered under the 1791 drought, but the relative degree of their struggles revealed the inequality between their positions. James Madison planned Montpelier’s biggest agricultural operations, including the cash crops and subsistence crops that would be grown on the plantation of over 9 square miles¹¹. His instructions in November 1790 to plant corn may have been part of a crop rotation with other grains, like the one shown in the image of a crop rotation scheme above left. In this scheme, “M.” represents corn, also known as maize, and plays an important role as a cash grain for the farmer.

However, the Madison family did not perform the labor of growing the corn, which would have been intensified by the drought. The image to the right shows the hard labor of harvesting: repeatedly pulling corn ears off the stalk and collecting the ears in baskets. At Montpelier, this work was carried out under force by the three hundred people the Madisons enslaved¹². Part of Madison’s 1790 instructions to overseers included creating new dams for irrigating crops, which likely helped during the 1791 drought¹³. Yet it is likely that enslaved people had to supplement this irrigation with hand watering and maintenance of the irrigation ditches.

This was difficult work for enslaved people to do on top of growing their own vegetables for subsistence and profit. For example, enslaved overseer Sawney grew his own sweet potatoes. Sweet potatoes represented a smart investment for enslaved people at Montpelier because their extensive roots help them tolerate drought better than most crops.¹⁴  Yet enslaved people like Sawney would have struggled to find time, energy, and water for even sweet potatoes while the Madisons forced them to spend these resources working on plantation crops like corn. Madison’s corn plan likely only yielded the “young corn” recorded on July 28th, known as baby corn today.¹⁵ Enslaved people’s crops must have struggled in the drought as well.

Droughts like the one that affected Montpelier in 1791 continue to harm crops today. Consider the 2019 drought experienced by people near James Madison’s Montpelier, the historic site exploring the history of the Madisons’ plantation.

This drought lasted roughly 30 days in the Montpelier area, from at least September 17 to October 22, damaging corn and other crops¹⁶. With Virginia’s longest drought in recent history lasting from May 1, 2007 to April 14, 2009, the 2019 drought is just one drought in a series of increasingly-common droughts¹⁷. These dry periods cost the United States economy nearly $9 billion per year¹⁸. Human-caused climate change continues to make these devastating droughts more common.¹⁹

Drought may even be affecting your area right now! If you live in the United States, you can use the United States Drought Monitor (USDM) to see if your region is experiencing drought: https://droughtmonitor.unl.edu/CurrentMap.aspx. Similar to the Madisons’ numerical and qualitative data collection, the USDM uses both numerical measurements and scientific observers to provide “a weekly assessment of drought conditions.” The Drought Monitor’s maps illustrate drought’s upward trend²⁰. In the 2014 National Climate Assessment, a project of the U.S. Global Change Research Program, scientists found that 10% of U.S. counties were at “high or extreme risk of water shortages.” Yet they predict that by 2050, 32% of U.S. counties will have this risk of drought—a 22% increase²¹.

Though drought threatens the crops we need to survive, you can help save those crops by speaking up for a healthier climate. One method of advocacy is contacting your governmental representatives and urging them to fund and implement climate action policy. Policies that reduce emissions can counter the climate change producing these droughts, and building better water infrastructure can help farmers adapt to drought conditions. If you live in the U.S. and are not sure who your representatives are, you can use https://www.usa.gov/elected-officials to find your representatives and their contact information. While the 1791 drought harmed the people of Montpelier and the crops they grew, effective climate policy can prevent worse droughts from happening in our shared future.