The removals have been accompanied by a new wave of opposition to the statues. On Saturday, a Houston man was taken into custody near a monument to Richard W. Dowling, a Confederate commander, in the city’s Hermann Park after a park ranger reported finding the man in possession of materials that could be used to make an explosive device.

The man, Andrew Schneck, 25, was charged with attempting to damage or destroy federal property, according to Abe Martinez, the acting United States attorney for the Southern District of Texas.

According to a criminal complaint released by the United States attorney’s office, Mr. Schneck told the ranger that he wanted to harm the statue and did not “like that guy.”

Meanwhile, the University of Houston announced Monday that it would be changing the name of a campus residence hall, the Calhoun Lofts, to the more innocuous “University Lofts.” Although the housing unit was not originally named for John C. Calhoun, the seventh vice-president and a strong defender of slavery, the school said that it was changing the name “in the wake of recent events, and out of sensitivity to our diverse student community.”

In Austin, three of the statues will be added to the collection of a campus historical center, where they will join a Jefferson Davis statue that was taken down in 2015 after a white supremacist killed nine black parishioners at a church in Charleston, S.C. The statue of Mr. Hogg was removed because it was a part of the broader exhibit, not because the university had ideological objections to its presence on campus, Mr. Bird said. The university is looking to find a new place for it on campus.

General Johnston was appointed to his post by Jefferson Davis in 1861 and given command of the Confederate army’s western department. He was killed in the battle of Shiloh in 1862. After resigning a congressional seat in the lead-up to the Civil War, Mr. Reagan served as the Confederacy’s postmaster general.

Austin is the Texas university system’s flagship campus. The school’s history, like that of many southern institutions, is intimately linked with the history of the Confederacy. A task force assembled to study the statues in 2015 said that removing the statue of Mr. Reagan might “put a target” on other buildings or spaces that honor Texans who fought in the Confederate army. The report noted that those Texans would include much of the university’s founding generation, including George Washington Littlefield, a regent and benefactor who commissioned the statues.