Since taking office, Mr. Trump has been focused on expanding oil, gas and coal development and sweeping away Obama-era environmental initiatives that the administration contends hurt America’s energy industry. The debate over shrinking national monuments sparked a fierce political battle, now being fought in the courts, over how much land needs federal protection.

Mr. Zinke has said that the agency review process made no presumptions about the outcomes. “We want to make sure that everyone’s voice is heard,” Mr. Zinke said at a news conference in May during a visit to Bears Ears. He has also disputed that the review of Bears Ears was related to the potential for energy production, suggesting that the agency’s own surveys showed there was not a great deal of potential there.

“We also have a pretty good idea of, certainly, the oil and gas potential — not much!” Mr. Zinke said last year. “So Bears Ears isn’t really about oil and gas.”

Most of the deliberations took place behind closed doors. The internal Interior Department emails — more than 25,000 pages in total — were obtained by The New York Times after it sued the agency in federal court with the assistance of the Media Freedom and Information Access Clinic at Yale University Law School. The lawsuit cited the agency’s failure to respond to an open records request in August asking for internal records related to the deliberations.

The bulk of the documents made public by the Interior Department — about 20,000 pages of them — detail the yearslong effort during the Obama administration to create new monuments, including input from environmental groups, Indian tribes, state officials and members of Congress. President Barack Obama created or expanded 29 national monuments during his tenure, representing a total of about 553 million acres, more than any of his predecessors.

The remaining pages, a total of approximately 4,500 files, relate to the Trump administration’s reconsideration of these actions by Mr. Obama and other presidents.

Heather Swift, the Interior Department spokeswoman, said in a statement that, in reviewing monuments, “The Secretary took into consideration the views of a variety of interested parties, such as members of congress, governors, state and tribal leaders, and the public, including the views of those parties as to possible revised monument boundaries. One such organization that weighed in was the State of Utah School and Institutional Trust Lands Administration (SITLA) which is responsible for funding so the children of Utah receive a quality education.”

Matthew Whitlock, a spokesman for Senator Hatch, said that the senator has been involved in discussions around Bears Ears for years. He emphasized that some of the land had long been designated to help fund local schools, and that Senator Hatch’s interest was to protect the school funding.

The internal Interior Department emails and memos also show the central role that concerns over gaining access to coal reserves played in the decision by the Trump administration to shrink the size of the Grand Staircase-Escalante National Monument by about 47 percent, to just over 1 million acres.

Mr. Zinke’s staff developed a series of estimates on the value of coal that could potentially be mined from a section of Grand Staircase called the Kaiparowits plateau. As a result of Mr. Trump’s action, major parts of the area are no longer a part of the national monument.

“The Kaiparowits plateau, located within the monument, contains one of the largest coal deposits in the United States,” an Interior Department memo, issued in the spring of 2017, said. About 11.36 billion tons are “technologically recoverable,” it projected.

From the start of the Interior Department review process, agency officials directed staff to figure out how much coal, oil and natural gas — as well as grass for cattle grazing and timber — had been put essentially off limits, or made harder to access, by the decision to designate the areas as national monuments.

One memo, for example, asked Interior staff to prepare a report on each national monument, with a yellow highlighter on the documents emphasizing the need to examine in detail “annual production of coal, oil, gas and renewables (if any) on site; amount of energy transmission infrastructure on site (if any).” It was followed up by a reminder to staff in June to also look at how the decision to create new National Monuments in Utah might have hurt area mines.

“Sorry about this, but this came from DOI late yesterday,” Timothy Fisher, the leader of the National Monuments and Conservation Areas program at Interior wrote to his colleagues, referring to the Department of Interior headquarters in Washington. “Are there mines or processing facilities near or adjacent to a National Monument?” he wrote. He also asked how the protection of the federal lands may have affected mining.

In another email exchange, in May, two Bureau of Land Management officials said that Mr. Zinke’s chief of staff for policy, Downey Magallanes, had phoned to ask for information on a uranium mill in or near the Bears Ears monument. The request sought “economic data to the extent available,” as well as grazing and hunting maps.

And on July 17, Ms. Magallanes and Mr. Zinke’s counselor for energy policy, Vincent DeVito, met with representatives of a uranium mining company. The company, Energy Fuels Resources Inc., said its representatives hoped to discuss its White Mesa uranium mill as well as the Daneros uranium mine, both adjacent to the Bears Ears monument.

In addition to Paul Goranson, a top executive at Energy Fuels Resources, the meeting included Mary Bono, a former Republican congresswoman from California; and Andrew Wheeler, then a lobbyist at the firm Faegre Baker Daniels Consulting and now awaiting confirmation to be deputy administrator of the Environmental Protection Agency.

Ms. Swift, the Interior Department spokeswoman, said that no uranium mine or milling operations were located within the boundaries of either the original or modified Bears Ears National Monument.

The debate over oil and gas reserves below the ground in Bears Ears started during the Obama administration, the documents show, with officials from Utah State Board of Education writing to the Interior Department objecting to the plan to designate the area as a national monument.

Before Utah became a state, in 1896, the federal government granted so-called trust lands to support state institutions, like the public schools, given that nearly 70 percent of the land in the state is federally controlled.

The state has generated more than $1.7 billion in revenue from the trust lands to support public schools, mostly by selling off mineral rights and allowing private companies to extract oil or gas. The Bears Ears National Monument created by President Obama in 2016 included about 110,000 acres of these trust lands, eliminating the potential for resource sales, the state said.

John Andrews, associate director of the Utah School and Institutional Trust Lands Administration, which oversees the lands designated for school funding, acknowledged that the new Bears Ears boundaries approved by Mr. Trump, which reduced the land removed from the trust’s management to about 22,000 acres, reflected his group’s request to exclude trust lands from federal protection.

But he noted that Mr. Trump ultimately reduced the monument by a much larger amount than his organization had sought.

“Obviously they were looking at facts other than the ones we had raised, we assume,” he said.

Mr. Whitlock, the spokesman for Mr. Hatch, said, “Senator Hatch is grateful these emails have been released because they make very clear that his priority in addressing the Bears Ears situation was looking out for the people of Utah.”