What Was the Guano Islands Act?

In 1856, a paralyzed and bickering Congress managed to pass exactly one piece of legislation. It was about bird poop. It's still the law.

BY AARON HELMAN // POSTED MAY 1, 2026

It's 1856, and Schuyler Colfax has a problem. He's been in Washington representing Indiana 9th Congressional District for barely more than a year, and it's time to start plotting his campaign for reelection. The trouble is that when he comes home, and people are going to ask him exactly what was accomplished during his time in D.C., he doesn't have a very good answer to share with them.

It wasn't really his fault.

The 34th Congress of the United States was probably the least functional legislative body in the history the United States up to that point. The nation wasn't quite divided enough to launch a Civil War, but it was getting there. Schuyler Colfax entered into a House of Representatives so fractured that it took 133 ballots and two months of screaming before they could even elect a Speaker.

It only got more dysfunctional from there. Pro-slavery and anti-slavery voices grew louder and hotter and angrier throughout 1856, until at last a pro-slavery congressman from South Carolina walked into the Senate Chamber and beat an anti-slavery senator from Massachusetts half to death with a metal-tipped cane. The attack came on the floor of the Senate in the middle of the afternoon. Southerners sent the congressman hundreds of commemorative canes as a show of support for an act that could only be described as attempted murder.

The incident was summary and metaphor of Colfax's first term in office, so when it came time to report home on the major legislation from his time in the nation's capital, there wasn't much to share.

But there was one thing. They'd managed to pass one law.

The only thing they could all agree on was thar bird poop...

...was good.

This probably requires some explanation.

In the 1850s, bird poop was a very big deal. Specifically, guano, which is the fanciest possible way of saying it. Guano was the accumulated excrement of seabirds piled up over centuries on remote and uninhabited islands, sometimes gathered to a depth of dozens of feet. It was high in nitrogen and phosphates, which made it the finest fertilizer in the known world, and in the years before synthetic fertilizers, farmers were absolutely desperate for it.

The craze was so intense that newspapers called it guano mania, which is a phrase that has not received nearly enough historical attention. The stuff was genuinely transformative. Corn and cotton yields could be tripled with a good application of guano. By 1850, guano accounted for 22 percent of all commercial fertilizer used in the United States. Ten years later, that figure had climbed to 43 percent.

But centuries-old bird poop was a finite resource, and the United States was running out of inexpensive ways to acquire it.

The solution, as proposed by New York Senator William Seward in early 1856, was both elegant and completely insane. He called it the Guano Islands Act, and it was passed by the House on August 16, 1856. President Franklin Pierce signed it into law two days later.

The premise of the bill was simple enough: If an American citizen discovered an unclaimed island covered in guano and no other government had gotten there first, that citizen could claim the island for the United States. The President could then, at his discretion, extend federal protection to that island. The U.S. Navy would show up. The guano would be mined and sold to American farmers at a reasonable price. Everybody wins.

The bill passed with remarkable speed for a Congress that couldn't pass a dinner order.

There was no sectional tension over guano. The North wanted it. The South wanted it. For one brief, glorious, utterly absurd moment in 1856, the United States Congress set aside its arguments about the fundamental moral question of human slavery and came together, as one nation, united by a shared appreciation for bird excrement.

The results were immediate and strange. American entrepreneurs flooded out into the Pacific and Caribbean, hunting for unclaimed islands with enough bird droppings to make a claim viable. Within a few years, nearly 100 islands had been claimed under the Act.

The Navy mobilized to protect the guano island claims. They sent warships to patrol remote Pacific waters to enforce American territorial rights over bird dung. Things got complicated almost immediately. Navassa Island, off the coast of Haiti, was claimed by American entrepreneurs in 1857. Haiti disagreed, since they had a treaty with France that included the island. The United States, backed by the legal authority of the Guano Islands Act, disagreed right back.

The dispute has never been fully resolved.

By 1903, 66 guano islands were officially recognized as U.S. territories. When the guano ran out on most of them, the law was very clear about what happened next: the United States had no obligation to keep them. Many were simply abandoned, left to the birds.

The ones that weren't abandoned turned out to be useful for other things. The guano islands became naval refueling stations, then military bases, and in one case, a storage and incineration site for Agent Orange during the Vietnam War.

That brings us back to Schuyler Colfax, who had to return to South Bend and account for his two years in Washington. Colfax would, of course, go on to have a significant career. He'd eventually become Speaker of the House and then Vice President of the United States. But in 1857, he was just a first-term congressman from northern Indiana trying to explain what his completely gridlocked Congress had managed to accomplish.

The answer was bird poop. It wasn't a very good answer, but it didn't keep Colfax from winning re-election. Indiana's 9th district kept sending him back to Washington for another twelve years.

As for the Guano Islands Act, it hung on even longer than Schuyler Colfax. In fact, it's still officially on the books today: Title 48, U.S. Code, sections 1411 through 1419. That means that you are authorized by the Federal government to claim uninhabited, guano-bearing islands on behalf of the United States.

Somewhere out in the Pacific Ocean, there are a few rocks that belong to the United States, long stripped of their valuable guano. Baker Island, Howland Island, Jarvis Island, and Johnston Atoll are still claimed under the legal authority of the Guano Islands Act, passed in 1855 by the most dysfunctional Congress in American history.