Having attained a critical mass that rendered it relatively secure against outside pressures, the Park Police experienced new and different pressures beginning in the late 1950s. Now its leadership came under attack and its police role was questioned from within the Interior Department. Its professionalism amid the violent demonstrations of the late 1960s and early 1970s was severely tested and sometimes criticized. During much of this period, the park policeman's lot was not a happy one.
In 1957 Donald S. Leonard of Detroit, a former president of the International Association of Police Chiefs and a consultant on police administration, studied the Park Police as part of a five-man team conducting an overall survey of the National Capital Parks organization for Secretary of the Interior Fred A. Seaton. Leonard found a variety of problems weakening the 190-man force, including frequent bypassing and undercutting of authority, poor discipline, low morale, and unsatisfactory promotion policies. All promotions were then in abeyance pending the outcome of a lawsuit by Sgt. John M. Gyakum, who charged that he had been bypassed improperly for promotion to lieutenant. 
Leonard recommended several changes: an immediate increase of 51 officers and a total force strength of 407 after ten years; more authority for the chief, who should report to the NCP superintendent rather than an assistant superintendent; establishment of a trial board for officers charged with offenses, with the chief empowered to suspend; more emphasis on youth in recruiting; training for all recruits before assignment to duty; greater authority and backing for supervisors; promotions restricted to the top three persons on eligibility registers. The recommendations were generally well received. Some of those that could be adopted administratively, like having the chief report directly to the NCP superintendent, were. Legal authority and appropriations were sought for the trial boards and increased strength. The force continued to grow, although at a lesser rate than Leonard proposed. 
But problems persisted, rising to unprecedented public visibility in 1961. Before his death that February, NCP Superintendent Harry T. Thompson had asked Peter J. Lejins, a University of Maryland criminologist, to investigate the Park Police. Lejins submitted his 67-page report, based on interviews with members of the force, in April. It portrayed the force as suffering from promotions and assignments based on favoritism, poor discipline, personal intrigues, and outside interference. Lejins found many stories circulating within the organization about corruption, sexual misconduct and drunkenness on duty, a battle between a former chief and a former NCP superintendent in which each sought to get rid of the other, and the need for political support to advance. It was alleged that "in order to survive in the Park Police the officer has to have a Congressman and a lawyer on his staff," and Lejins was shown letters from members of Congress recommending certain men for promotion. All this dirty linen was aired in a Washington Post story at midyear. 
Secretary of the Interior Stewart L. Udall and Assistant Secretary John A. Carver, newly arrived with the Kennedy Administration, determined to shake up the organization. Having learned of anonymous letters to the Interior Department on police matters, Carver met publicly with the force in March and advised them against going outside channels with grievances. Unsigned letters to the Secretary would not be read, he warned. 
The greatest clamor arose over Secretary Udall's efforts to oust Chief Harold F. Stewart. In charge of the force since 1954, Stewart was perceived in some quarters as "old guard" and resistant to reform. Udall offered his job to Robert J. Mangrum, a black former New York deputy police commissioner, but Mangrum declined, noting that the job paid less than his current position and would require him to uproot his family. Udall's offer was also premature, for as Civil Service Commission Chairman John Macy confirmed, the Park Police chief held a merit position not subject to patronage. Stewart could not be removed except for cause, and he declared that he had no intention of resigning under pressure. 
Meanwhile, Assistant Secretary Carver revealed plans to reshape the Park Police along park ranger lines. Their blue police uniforms would give way to green ranger uniforms, and they would devote at least as much attention to interpretation as to law enforcement and traffic control. The force would be headed by a ranger with a naturalist's background, and openings would be filled by people of similar experience. "The reaction of a visitor to a green-suited ranger rather than to a man in a blue uniform with a badge would be entirely different," Carver told the Washington Post. As for the recalcitrant Stewart, Carver hinted that he might be reassigned to handle traffic jams in Yellowstone. 
The Evening Star denounced Udall's "unauthorized" offer of Stewart's job to Mangrum and viewed the plan to convert the Park Police to a "ranger outfit" headed by a ranger as an improper device for getting rid of the chief. The ability of rangers "to cope with the rapists, child molesters, sex perverts and other criminal types which have operated in local parks" was highly questionable, in its opinion.  Undeterred, Interior's leaders proceeded in September to concoct a detail for Stewart more distant by far than Yellowstone: he was assigned to study police requirements on Guam!
The Washington Post, deeming Stewart's exile justified after his unwillingness to retire, editorialized facetiously on "The Advantages of Travel": "Guam was chosen for Chief Stewart's next assignment because, like St. Helena, it is a small island that presumably offers few opportunities for either great deeds or mischief. Behind him, Mr. Stewart will leave a small but expensive police force, largely superfluous in its duties, and corroded for decades by political meddling, vindictive personal feuding, and a tradition of unpunished improprieties." The Post thought the ranger idea a fine one. 
Carver ordered Nash Castro, a recently appointed NCP assistant superintendent, to act in Stewart's place. When Castro protested his complete lack of police experience, Carver assured him he would learn soon enough. Castro moved from NCP headquarters in the Interior Building to Park Police headquarters, the old Fisheries Laboratory at 7th Street and Independence Avenue occupied by the police since 1952. He found the force in chaos, its morale invisible. To get acquainted and show his interest in their work, he went on patrols with the men. He got them involved in training courses to keep them busy and distract them from dissention. He won their support for discontinuing the solicitation of liquor and food from local merchants as prizes for police pistol matches. 
In March 1962, with the approval of Acting NPS Director Hillory A. Tolson, Castro arranged additional exiles for two other veteran Park Police officials he found contributing to factionalism within the force. Lt. Jack B. Hobbs was sent to Independence National Historical Park in Philadelphia, while Lt. Vincent W. Cleary was detailed to Jefferson National Expansion Memorial in St. Louis to work out "protective arrangements for buildings and grounds." Hobbs responded tersely to a question about his detail: "Well, let's say I didn't ask for it." 
Chief Stewart spent the last three months of 1961 on Guam, returned to Washington at the end of the year, went back to Guam to supervise the implementation of his recommendations for revamping its police force, then came home in April 1962 to write a report about his assignment. NPS Director Conrad L. Wirth told the press that Stewart was being considered for another project that "would utilize his vast knowledge of police administration." The project proved to be an expansion of his report; his duty station was his home. This was because of a lack of office space for him and because his wife helped with the typing, the press was told. 
Meanwhile, Rep. J. T. Rutherford of Texas, chairman of the House Interior Committee's subcommittee on parks, introduced legislation in Congress to authorize the trial boards and administrative punishments recommended by Donald Leonard five years before. His bill would allow fines and suspensions without pay for more than three days after internal trial board proceedings at which accused officers were entitled to counsel.  At a March hearing on his bill, Rutherford said he had "all I am going to take" of pressures to intercede in police disputes and promised legislation to terminate the Park Police if bickering by "knotheads" on the force continued. 
Speaking on the House floor before passage of his bill there in April, Rutherford explained it as providing the same means for handling minor disciplinary problems as existed in other police organizations. He continued:
"If this bill and other changes which the Department of the Interior have been making do not substantially lessen internal conflict in the Park Police and improve its standing in the eyes of the citizenry," Rutherford warned again, "I shall move quickly to introduce a bill to abolish the Park Police and transfer its functions to the Metropolitan Police and other organizations." 
Rutherford's bill was signed into law that October, a month after the Park Police got a new leader.  Feeling that he had done all he could to improve the situation, Nash Castro had requested a permanent replacement so he could return to his civilian duties. Nelson Murdock, a veteran park ranger lately chief of visitor protection for the National Park Service, thereupon became the first deputy chief of the force, assigned to act as chief pending Stewart's retirement and succeed him. In announcing Murdock's appointment, Director Wirth said he had been selected with the idea that the force would function more as a dispenser of information to the public and less as a law enforcement agency. 
The Post praised Murdock's selection and anticipated that the shift to ranger uniforms would follow. "His arrival suggests that the Park Police will progressively be devoted to helping visitors enjoy the Capital's park system," it editorialized. "In the past, they have been merely another vest-pocket law enforcement agency, spending most of their time on routine patrolling that the District's Metropolitan Police can handle far more efficiently."  In contrast, the Star, noting Stewart's support for the trial board reform, deplored the way he was being treated:
Seeking to make amends at year's end, Wirth publicly called Stewart's completed 495-page report "one of the finest ever produced by the Department." He expected Stewart to retire "within the next month" on disability.  In fact, Stewart stayed on until March 31, 1963. The Post described his departure as "an end to the old guard who have run the force for a decade" and saw a "new era" ahead. Interviewed by the Star in May, Chief Murdock saw morale much improved following the retirement of several dissidents elsewhere in the force and actions by Congress to authorize the trial boards, raise pay, and increase the size of the force, easing workloads and opening up promotion opportunities. 
Morale was also improved by the quiet shelving of the plan to "rangerize" the force, a very unpopular idea within the organization.  If any support for deemphazing law enforcement in the Park Police remained, it was surely dispelled amid the violent demonstrations and increased lawlessness of the late 1960s and 1970s, when instead of policemen becoming more like rangers, rangers had to become more like policeman.
The Poor People's March on Washington in 1968 begot the Resurrection City encampment in West Potomac Park south of the Reflecting Pool, one of the first major demonstrations handled primarily by the Park Police rather than the Metropolitan Police. Attorney General Ramsey Clark and other officials allowed the participants to remain well beyond their alloted time and gave them virtual immunity from criminal arrest as the camp degenerated into a lawless morass, making Resurrection City a notably thankless assignment for the force. 
Events of 1970 were particularly stressful, not only in Washington's parks but elsewhere in the national park system. During the Fourth of July weekend an unruly crowd of young people took over part of Yosemite Valley, leading to a violent clash with park rangers unaccustomed to riot control. A Park Police contingent was detailed there soon afterward to help maintain order. In Washington the Fourth of July became a mob scene. An "Honor America Day" program led by Bob Hope and Billy Graham at the Lincoln Memorial was countered by screaming youths around and in the Reflecting Pool who pushed vehicles into the pool and threw rocks and bottles at the mounted park policemen trying to hold them back from the ceremonies. Mob violence, vandalism, and open drug use continued during the evening fireworks display and through the night.
As their horses were cut by thrown broken bottles and in the face of other extreme provocations, some park policemen overreacted. This prompted some critics to question the professionalism of the force in responding to such episodes. A Washington Post article addressed the issue:
Grant Wright, chief during the difficult period from 1968 to 1973, was quoted as disagreeing with this assessment. But the article portrayed Metropolitan Police Chief Jerry Wilson as more often in personal command on the scene than Wright, who was inclined to delegate control to Deputy Chief Alfred Beye, an old-school cop overtly hostile to demonstrators. 
The 1970 disorders prompted a $550,000 supplemental appropriation to the National Park Service for law enforcement in fiscal 1971. (Coincidentally, that was the year in which partial funding of the Park Police by District of Columbia appropriations was discontinued, removing one of the old rationales for having the District absorb the force.) The money was needed: violence again disrupted Washington as May Day demonstrators tried to shut down the government, and lawless elements became a growing threat in other national parklands.
Law enforcement was a major topic of discussion at the Park Service's budget hearings before its House appropriations subcommittee in April 1971. NPS Director George B. Hartzog, Jr., testified that the Service had considered forming a national park police organization but decided against doing so on the recommendation of the International Association of Police Chiefs. Instead, they had established in their Washington Office a Law Enforcement Division headed by Park Police Inspector Franklin A. Arthur and were assigning a Park Police captain to each NPS regional office to coordinate law enforcement in the parks. "We will also detail an officer to the 15 or 20 parks in which we have been having major law enforcement problems over the last few years," he announced, mentioning Grand Canyon, Grand Teton, Great Smoky Mountains, Lassen Volcanic, Mount Rainier, Olympic, Yellowstone, and Yosemite national parks; Cape Cod, Fire Island, and Point Reyes national seashores; Blue Ridge and Natchez Trace parkways; Badlands National Monument; Lake Mead National Recreation Area; and Ozark National Scenic Riverways. A strike force of 125 privates under an officer would be maintained in the National Capital Parks, available to reach trouble spots anywhere in the park system on 12 hours' notice. The strike force had already been sent to Death Valley National Monument when trouble threatened there that Easter weekend. 
During 1972 park policemen were assigned at various times to Big Bend, Grand Canyon, Rocky Mountain, and Yosemite national parks; Delaware Water Gap and Lake Mead national recreation areas; Cape Cod and Padre Island national seashores; Blue Ridge and. Natchez Trace parkways; and Statue of Liberty National Monument.  These details in the early 1970s foreshadowed a significant expansion of the force beyond the national capital area and coincided with noteworthy improvements in its training, equipment, and overall capabilities. The maturing of the United States Park Police to become one of the nation's elite law enforcement units will be recounted in the concluding chapter.