Historic U.S. Droughts That Permanently Altered the Landscape

Droughts have a major impact on the ecosystem. When they occur, scientists can tie the event to many other adverse effects on the ecosystem. Insect populations tend to flourish during droughts as insects don't need much water compared to other species. Plant growth will recede and may not be able to recover. Wildfires become more common as the drought dries out plant growth and increases air temperatures.

A long period of dry weather may have long-term adverse effects on the ecosystem as well. Lakes may dry up. Watersheds may not recover. The balance of species may be irreparably harmed. Let's look at the worst droughts ever recorded in American history.

To populate this list, we started by looking at a study done in 2017, A Comparison of the Early Twenty-First Century Drought in the United States to the 1930s and 1950s Drought Episodes that identified and compared major drought events in the United States. Then, we took that information and looked at the long-term effects on the affected areas to better understand the consequences of these drought events. We ensured that the sources we looked at were primarily peer-reviewed studies and major local news sources that had access to the necessary data to make sound conclusions.

Heim's study defines a "drought" as a prolonged period under which the natural weather patterns disrupt the water supply and water demand in an area. In other words, when the precipitation in an area is not sufficient to replace the water we are using, our area is considered to be in a drought episode.

Many people assume a drought must be exceptionally severe to "count." However, scientists identify droughts of all types of severity. They look only for a statistically significant difference between the area's water supply and demand to identify a drought. That does not require people to be dying, simply that the water supply in an area is steadily going down instead of being maintained.

Droughts are also associated with higher temperatures. However, this association is primarily a misconception of the general public. A drought requires drier than normal weather but not necessarily hotter than average. The definition of a drought depends largely on local weather. Different areas have different "normal" amounts of precipitation. Thus, it wouldn't make sense to declare a drought in one area based on the weather of another. In Bali, six days of no rain is considered a drought. However, in Libya, the definition of a drought is when the annual precipitation totals less than 7 inches, which is less rain than Bali gets in a month, sometimes.

The American Meteorological Society identified more than 40 periods of drought somewhere in the United States between 1900 and 2014. Of these 40 events, they consider 13 periods as "major" drought events. In a major drought event, the affected area of the United States equals 10% or more of the Contiguous United States (CONUS), which excludes Alaska and Hawai'i, for at least 90% of the drought period.

The three longest United States drought periods occurred between June 1928 and May 1942 (The Dust Bowl Drought), July 1949 and September 1957 (The 1950s Drought), and June 1998 and December 2014 (The Early 21st Century Drought). However, the National Integrated Drought Information System notes that from the years of 1895 until 2010 around 14% of the CONUS was experiencing drought conditions at any time on average.

During the 1930s, the southern plains regions of the United States endured the Dust Bowl Drought. Many factors went into the drought's effects but the most poignant effect of the event was the exacerbation of the Great Depression. Changes to the natural weather patterns of the southern plains were the primary cause of the dryness in the air. However, man-made issues caused devastating natural disasters that the weather exacerbated.

The Dust Bowl Drought ties very strongly into the American ideal of "Manifest Destiny." Now recognized as a deeply flawed and detrimental belief, Manifest Destiny stated that American settlers were predestined by God to expand the United States territory across Western North America. Manifest Destiny is the root cause of many tragedies, including the Native American Wars and the Dust Bowl Drought. Due to the propagation of Manifest Destiny, the United States government heavily incentivized American farmers to build agricultural settlements in the Western Territories. However, these areas are not as hospitable to agriculture as other areas.

Many wheat farmers moved out West during the Western Expansion of the United States. However, when the Great Depression hit, the sale price of wheat plummeted and many of these farmers could not make ends meet. As a result, they tore up the deeply rooted plains grasses to yield other crops. When they did so, they exposed the dry, dusty ground to the elements. As the drought started and rain became less plentiful, the dust started to pick up in the winds. This caused severe dust storms in the area that devastated settlements, killing crops, humans, and livestock alike.

Another major, long-term drought occurred in the United States, starting in 1949 and lasting until 1957. According to the National Ocean and Atmospheric Administration, the 1950s Drought was the most widespread and severe in U.S. history to date. However, despite its severity, NOAA indicates that the drought garnered significantly less attention than the previous Dust Bowl Drought. This is in no small part due to the timeframe. NOAA notes that droughts of shorter periods garner less media and public attention, even if they are more severe and have stronger long-term impacts.

The 1950s Drought had characteristics of both unusually dry weather and also hot weather, which increased the risk of certain side effects of drought. However, the socioeconomic factors of the time resulted in the minimization of the coverage and public knowledge of the event. The study, Bite without bark: How the socioeconomic context of the 1950s U.S. drought minimized responses to a multiyear extreme climate event by Wiener, et al. delves into the factors that caused the lack of media and public attention to such a devastating and widespread climatological event.

NPR assesses the long-term effects of the 1950s Drought on the agricultural sector in Texas, the most affected area of the event. Many farmers and ranchers were unable to support their families during the drought due to the changes in the environment. The dry land was unable to grow crops and the livestock suffered from lack of nutrition and water. These issues resulted in many abandoning agriculture in the area, sometimes for good.

At the turn of the 21st century, the droughts were plaguing the CONUS. Starting in 1998, droughts began to crop up all over the United States and by 2012 almost 2/3 of the CONUS was in a state of drought. Many began to speculate that the Early 21st Century Drought was as bad as the Dust Bowl and 1950s Droughts. Heim's study assesses the effects of the Early 21st Century Drought and compares its severity to the other two major drought episodes from the CONUS.

The Early 21st Century Drought received better documentation than previous droughts due to better technology for measuring the presence and effects of droughts. Additionally, greater attention to climate change caused more interest in the presence of droughts and how they affect the long-term climatological changes the Earth is undergoing.

The droughts of the 21st century, including both the major drought episode from 1998–2015 and all the isolated droughts that have occurred since have had significant impacts on the ecosystems in affected areas. Grasslands have become drier and are struggling to adapt to the grass mortality caused by the drought. Wildfires continue to threaten the flora and fauna in areas that have not recovered. Watersheds in some areas may never recover from the severe effects of the droughts.

The effects of droughts in the 21st century aren't unique to the United States; ecosystem changes are occurring worldwide due to droughts. Wildfires in the Amazon from the 2015 drought in the area caused mass flora and fauna mortality.