Administered by the U.S. Fish and Wildlife Service (FWS) and the National Oceanic and Atmospheric Administration (NOAA), the ESA still prohibits anyone from collecting, pursuing, capturing or harming a protected species on the list or disturbing "the ecosystems upon which they depend."
Once a species reaches the point of endangerment, government agencies are required under the law to take active measures to save it, notwithstanding pressure from extractive industries like logging and mining.
To help conserve genetic diversity, the ESA also mandates the protection of subspecies and distinct population segments of a species under certain circumstances. For example, while grizzly bears in the continental U.S. are listed as threatened, the abundant Alaskan population of grizzlies is not.
“Nothing is more priceless and more worthy of preservation than the rich array of animal life with which our country has been blessed,” President Nixon said at the signing ceremony on Dec. 28, 1973. “It is a many-faceted treasure, of value to scholars, scientists and nature lovers alike, and it forms a vital part of the heritage we all share as Americans.”
The law was a bipartisan reaction of alarm to the dramatic decimation of wildlife in America occurring over several centuries of accelerating growth and development.
And by most accounts, it has worked incredibly well.
In the more than four decades since its passage, only 11 of the more than 1,600 species protected under the ESA have gone extinct -- and 51 other species formerly included have since been delisted following a resurgence in their numbers. All that despite a tripling of the nation’s gross domestic product and a population increase of more than 100 million people.
Today, almost 1,300 plant and animal species in the U.S. are listed as endangered (which receive all the protections of the law) and close to 400 more are listed as threatened (which get some protections).
But despite the overwhelming bipartisan support the ESA once garnered -- and its continued public approval -- the measure has long been under attack. And that’s largely because of just how effective it’s proved to be in protecting vulnerable species.
The law’s power and reach was made clear in 1978, when a federal dam project in Tennessee was blocked to protect a tiny endangered fish called a snail darter. Ever since, opponents have denounced the ESA as blatant federal overreach that infringes on property rights and thwarts much needed economic development, particularly in rural, under-resourced communities.
Critics question the law’s mandate to identify and protect certain species without considering the economic consequences of those actions. Is it really worth conserving the habitat of an obscure plant, insect or tiny fish, particularly if doing so stands in the way of creating new jobs and economic opportunities?
Those seeking to water down the ESA now see a major opportunity with a Republican-controlled Congress and the staunchly anti-regulatory attitude of the Trump administration.
A handful of recently introduced bills, some of which have been floating around Congress in some form or other for decades, could significantly weaken the scope of the law. One would prevent threatened species from being listed if doing so could have economic repercussions. Another bill would require federal agencies to consider data submitted by state or local governments when evaluating if new species should be protected, a rule change that environmentalists fear would result in a slew of biased or inaccurate information to influence the decision-making process.
But as our latest Above the Noise video explains, supporters of major conservation efforts like the ESA counter that it's not only our ethical responsibility to protect native species from extinction, it's also downright crucial to the earth's survival: "Living things in an ecosystem depend on each other. And the disappearance of one species could have big impacts on the whole thing."
In fact, some scientists argue that we're currently in the midst of a sixth major mass extinction, with the rate of species disappearance estimated to be anywhere from 1,000 to 10,000 times faster than the historical average. And unlike previous mass extinctions in earth's history, this one can be largely blamed on us: humans.
To get a clearer sense of just how fast and how many species around the world are vanishing, explore this interactive, produced by ProPublica, which uses data from the International Union for Conservation of Nature's Red List of Threatened Species.