The Antiquities Act is a conservation tool authorizing the President to designate National Monuments through a Presidential Proclamation. It was signed into law in 1906 (Public Law 59–209) by President Teddy Roosevelt in response to looting, desecration, and destruction of Native American sites in the American Southwest. The Act provides broad authority for the President to to set aside “historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest.” Roosevelt quickly went to work in protecting 18 areas of both historic and scientific interest as National Monuments including 800,000 acres of the Grand Canyon that he designated as a National Monument and would later become Grand Canyon National Park.

The language on establishing a National Monument by the President contained within 54 U.S. Code § 320301 is quite simple and reads as follows:

a) Presidential Declaration.— The President may, in the President’s discretion, declare by public proclamation historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest that are situated on land owned or controlled by the Federal Government to be national monuments.
b) Reservation of Land.— The President may reserve parcels of land as a part of the national monuments. The limits of the parcels shall be confined to the smallest area compatible with the proper care and management of the objects to be protected.
c) Relinquishment to Federal Government.— When an object is situated on a parcel covered by a bona fide unperfected claim or held in private ownership, the parcel, or so much of the parcel as may be necessary for the proper care and management of the object, may be relinquished to the Federal Government and the Secretary may accept the relinquishment of the parcel on behalf of the Federal Government.
d) Limitation on Extension or Establishment of National Monuments in Wyoming.— No extension or establishment of national monuments in Wyoming may be undertaken except by express authorization of Congress.

While National Monuments are focused on historic and scientific features, many provide opportunities to experience these features through outdoor recreation. The list below highlights those with opportunities for paddlesports. At least two National Monument Proclamations directly recognize these paddlesports. The Bears Ears National Monument Proclamation notes the “world class outdoor recreation opportunities” that include “whitewater rafting” and the Browns Canyon National Monument Proclamation notes that the “area also provides world class river rafting and outdoor recreation opportunities.”

Bears Ears National Monument in Utah, proclaimed by Obama in 2016 (1.35 million acres). One of the best family-friendly raft trips in Utah can be enjoyed on the San Juan River that forms the southern boundary of this National Monument.

Browns Canyon National Monument in Colorado, proclaimed by Obama in 2015 (21,586 acres). The Brown's Canyon section of the Arkansas River is a popular and well-known whitewater boating destination.

Cascade-Siskiyou National Monument, proclaimed by Clinton in 2000 and enlarged by Obama in 2017 (100,000 acres). The public lands surrounding the Upper Klamath River are included as part of this National Monument.

Dinosaur National Monument in Utah, proclaimed by Wilson in 1915 (210,000 acres) includes the Yampa River and Gates of Lodore section of the Colorado River.

Giant Sequoia National Monument in California, proclaimed by Clinton in 2000 (327,760 acres). A National Monument protecting 33 giant sequoia groves, the Middle Fork Tule flows through it with the Kern River to the eastern edge.

Gold Butte National Monument in Nevada, proclaimed by Obama in 2016 (296,937 acres). Grand Canyon river runners who float to South Cove and spend their last night in Ice Box Canyon are close to this wild country held between the arms of Mead Reservoir representing the end of the Virgin and Colorado Rivers respectively.

Grand Canyon-Parashant National Monument in Arizona, proclaimed by Clinton in 2000 (1 million acres). This National Monument north of Grand Canyon National Park extends along the Shivwits Plateau from Lava Falls down to Mead Reservoir.

Grand Staircase-Escalante National Monument in Utah, proclaimed by President Clinton in 1996. (1.7 million acres). This National Monument includes the spectacular canyon country in Utah including the Escalante River that is known as an overnight trip for kayakers and pack rafters.

Hanford Reach National Monument in Washington, proclaimed by Clinton in 2000 (194,450 acres). While not a whitewater reach, the last free-flowing stretch of the Columbia River is within this National Monument that provides opportunities for canoeing.

Katahdin Woods and Waters National Monument, proclaimed by Obama in 2016 (87,563 acres). This National Monument includes the East Branch of the Penobscot River. While this National Monument is below the 100,000 acre threshold, this Monument is being reviewed to "determine whether the designation was made without adequate public outreach.

Rio Grande del Norte National Monument in New Mexico, proclaimed by Obama in 2013 (242,555 acres). The Wild and Scenic Rio Grande River, one of our nation's original 8 Wild and Scenic Rivers, flows through this National Monument that includes the Taos Box run.

Upper Missouri River Breaks National Monument in Montana, proclaimed by Clinton in 2001 (377,346 acres). Although this section of the Missouri River is flatwater, it is a spectacular multi-day canoe trip and one of the few places left where one can experience a night under the stars at the same campsites Lewis and Clark used on their journey West in 1805.

Vermilion Cliffs National Monument in Arizona, proclaimed by Clinton in 2000 (279,568 acres). The Paria River and the spectacular geology to the West of Lee's Ferry on the Colorado River is included in this National Monument.

As evidenced by Grand Canyon, a number of National Monuments have later been designated as National Parks by Congress. Some of these protected lands that provide paddling opportunities include the following: Grand Canyon National Park (T. Roosevelt, 1908), Olympic National Park in Washington (originally Mount Olympus, T. Roosevelt, 1909), Zion National Park in Utah (originally Mukuntu-Weap, W. Taft, 1909), Katmai National Park and Preserve in Alaska, (W. Wilson, 1918), Black Canyon of the Gunnison National Park in Colorado (H. Hoover, 1933), Capitol Reef National Park in Utah (F. D. Roosevelt, 1937), Channel Islands National Park in California (F. D. Roosevelt, 1938), Grand Teton National Park (originally Jackson Hole) in Wyoming (F. D. Roosevelt, 1943), Aniakchak National Monument & Preserve in Alaska (J. Carter, 1978), Denali National Park in Alaska (J. Carter, 1978), Gates of the Arctic National Park and Preserve in Alaska (J. Carter, 1978), Lake Clark National Park and Preserve in Alaska (J. Carter, 1978).