When presidents approach the end of a term, an otherwise little-known federal law often hits the headlines. It’s the Antiquities Act, passed by Congress in 1906.

One of the landmarks of the Progressive Era, it made it a federal crime to collect or destroy any historic or prehistoric object or building on federally owned land. It also allowed the president of the United States alone to proclaim national monuments, without an act of Congress.

The law was provoked by widespread vandalism of archaeological sites, especially in the southwestern states. The dire situation led to a campaign calling for federal protection of the sites and their contents.

But the law quickly was used in ways some of its supporters had perhaps not intended. Immediately upon signing the law, President Theodore Roosevelt declared Devils Tower in Wyoming the nation’s first national monument. Then came Petrified Forest and Grand Canyon national monuments, and later Arches and Capitol Reef.

The Colorado Plateau also boasts many archaeologically oriented national monuments created under the act: Aztec Ruins, Bandelier, El Morro, Hovenweep, Canyons of the Ancients, and others.

More controversially, presidents have used the act to save much more than human antiquities. It’s been extended to protect larger natural landscapes, such as two million acres of the Grand Staircase-Escalante in southeast Utah.

In July President Obama used the law to proclaim new national monuments in California, Nevada, and Texas. Is he done using the law? We’ll have to wait until January 2017 to find out.