Bison, or buffalo, which almost succumbed to extinction after years of being hunted, is one step closer to being the United States National Mammal. Environmentalists dub it as the biggest symbol to represent the success of their conservation efforts.

On Tuesday, US Congress has approved the National Bison Legacy Act and it passed the Senate on Thursday.

Tribes and conservationists with their allies in the government have long been campaigning to make Bison the first national mammal of United States with an aim to"restore bison to Indian nations in a manner that is compatible with their spiritual and cultural beliefs and practices."

Jim stone, Executive Director for the Intertribal Buffalo Council, says the buffalo has played historical, cultural, and economic significance in the United States - therefore it should represent the United States.

"The Buffalo is an iconic species in this country. You have a bald eagle, which is recognized as a symbol, and it's very deserving of that position, yet the buffalo had more to do with the United States, pre-discovery, than the bald eagle in some senses. It provided everything for the Native American's way of life", said Stone in a press release.

The bill, currently waiting for President Obama's signature to become a Law, enumerates some of the reasons why Bison should be recognized as a symbol such as the animal being historic and being integrally linked with the economic and spiritual lives of many Indian tribes through trade and sacred ceremonies.

It also highlights some of the conservation efforts that have been done to save the animal from the edge of extinction in the 19th century.

As reported by The Guardian, The US army had a policy to kill off bison to harm the Native American tribes that relied upon them, as well as to make way for farmland and for food.

"Tourists paid to slaughter the animals and bison killing contests were popular - one person from Kansas managed to shoot 120 bison in just 40 minutes," the article notes.

Tens of millions of bison once flourished across Canada and Mexico. Today, just a handful of bison lived in Yellowstone National Park  with population swelling to roughly 4,900, Washington Post notes.

An estimated 20,000 bison live on public lands in North America; 162,110 live on private farms and ranches, according to the 2012 U.S. Department of Agriculture census.

Aside from being proposed a national symbol, Bison has been adopted by 3 States as the official mammal or animal of those States and has been depicted on the official seal of the Department of the Interior since 1912.