The Museum of New Mexico needed a full-time curator to assist them in installing new exhibits, and they found a willing candidate—author and historian John Leslie Sinclair.  Sinclair’s background made him uniquely qualified for the position in Lincoln. Disinherited by his aristocratic Scottish family, Sinclair spent fourteen years working as a cowboy, including in Lincoln County, before moving to Santa Fe to pursue a career in writing. In 1936, the Museum of New Mexico employed Sinclair to write articles regarding upcoming exhibits at the Palace of the Governors. Then, in 1940, the museum hired as the Courthouse Museum’s first full-time curator.  

When John Sinclair arrived in Lincoln, community members were planning and preparing for a unique event that would ultimately become a significant driver of tourism for the town. In 1934, state and local leaders in New Mexico began discussing commemorating the four-hundredth anniversary of the European settlement of New Mexico by Francisco Coronado. In 1935, the state legislature created the New Mexico Coronado Cuarto Centennial Commission and tasked the group with planning a year-long celebration in 1940. Headed by the University of New Mexico President J.F. Zimmerman, the Coronado Commission solicited ideas from communities across the state to fulfill Governor Clyde Tingley’s desire to host more than a dozen historic pageants as part of the celebration. 

The residents of Lincoln County, led by Senator Louise Coe and artist Peter Hurd, brought an exciting proposal to the table.  The community members suggested performing an outdoor folk pageant, retelling the story of Billy the Kid, on the grounds of the historic courthouse in Lincoln. As artistic director and star, Hurd wrote the script for the play based on previous work by Santa Fe novelist and playwright Phillip Stevenson. In 1931, Stevenson wrote the playscript for an outdoor folk pageant called Sure Fire: Episodes in the Life of Billy the Kid, performed for the first time during the annual Santa Fe Fiesta.  Hurd adapted Stevenson’s play, renaming it Billy the Kid Lives Again. Organizers set the performance date for June 22, 1940, and surrounded the debut with additional events.

John Sinclair resigned from his position in Lincoln on November 15, 1942, and moved to Tucson to focus on his writing career.  Sinclair's departure surprised the Museum of New Mexico and left them without an immediate replacement, and for the next few years, temporary curators filled the position. That changed in 1947, when former Territorial Governor George Curry accepted reappointment as State Historian, with the caveat that he be allowed to move to Lincoln and reside in the curator’s residence at the Courthouse Museum. The Museum of New Mexico agreed to the plan, and Curry took on the additional title of the Old Courthouse Museum custodian and moved into the building in May 1947.  Within days of taking over, Curry began working on updating exhibits in the courthouse, primarily with items from his private collection. In August 1947, Curry hosted a reception at the Courthouse Museum celebrating the fiftieth anniversary of his leaving Lincoln County in 1897. Curry invited “all old-time residents of Lincoln County” and sitting governor Thomas Mabry, ex-governors John Miles and J.F. Hinkle, and Brigadier General Hugh M. Milton II—recently apportioned as president of New Mexico State University.  Curry fell ill shortly after this gala affair and died on November 27, 1947, at the Albuquerque Veterans Hospital outside of Silver City, New Mexico. 

Following George Curry’s death, the Museum of New Mexico reevaluated the situation in Lincoln, employing journalist William Robinson of the “Roswell Morning Dispatch” and history professor Colonel Maurice Garland Fulton from the New Mexico Military Institute to analyze operations at the Courthouse Museum. Fulton and Robinson’s evaluation and recommendations galvanized the Museum of New Mexico to act. In 1948, the museum offered Colonel Fulton a full-time position as superintendent of Lincoln State Monument. When Fulton took over in Lincoln, the Museum of New Mexico’s budget was in dire straits, and a decade of deferred maintenance on the restored courthouse was beginning to take its toll. Local frustration with the Museum of New Mexico’s operation in Lincoln encouraged community members to explore establishing an independent commission to run the branch museum. In 1949, the state legislature approved Senate Bill 213, creating the Old Lincoln County Memorial Commission. Signed into law by Governor Thomas Mabry, the commission’s mandate was simple—to supervise operations at the Old Lincoln County Courthouse Museum and the Lincoln State Monument. The commission consisted of nine members, one appointed by the governor from each of the counties formerly part of Lincoln County and one from the state at large.  Beyond the commission's creation, the authorizing legislation also appropriated a modest annual budget of $10,000.00 to maintain and run the museum.  The first nine members of the commission included longtime Lincoln resident Burt Pfingsten and Lea County resident Dessie Sawyer—mother of pioneering female rodeo star Fern Sawyer.  The commission elected Dessie Sawyer, who also served as the Chairwoman of the New Mexico Democratic Party, as its first chairwoman. Sawyer, Pfingsten, and the rest of the commission saw great potential for the Courthouse Museum and Lincoln as significant contributors to the region’s tourism economy. 

One of the commission's first significant projects was the resurrection of the “Day in Old Lincoln” festival and the Billy the Kid folk pageant. In 1949, the commission partnered with the Lincoln County Historical Society to hold the Last Escape of Billy the Kid pageant and festival for the first time since 1940. The Old Lincoln County Memorial Commission provided space for the outdoor performance on the grounds of the courthouse museum and organized additional events around town. Peter Hurd reprised his role as Billy the Kid in the play, now called “The Last Escape of Billy the Kid.”  The Old Lincoln County Memorial Commission utilized the event as a fundraiser for the Courthouse Museum and other projects, and their vision paid off. The resurrection of the event became an annual occurrence, contributing significantly to public support for preserving Lincoln and enhancing the museum at the courthouse. 

During the 1950s, the commission and its staff significantly expanded their effort to preserve the town beyond the courthouse museum. In August 1952, the commission named John Lewis Boylan, the new curator of the Courthouse Museum. John and his wife, Nan, worked as a team in Lincoln. During their time at the courthouse, the Boylans spearheaded several significant exhibit projects, including restoring and reconstructing the second-floor courtroom and reinstalling the original 1,200-pound Diebold Safe and Lock Company vault door. On June 20, 1954, nearly two hundred people crammed into the courtroom during the dedication ceremony for the new exhibit. Those in attendance included Governor Edwin Mechem, former New Mexico Attorney General Ott Askren, and former U.S. Deputy Marshal Dee Harkey. Presiding over the affair was 84-year-old Charles Brice, former Chief Justice of the New Mexico Supreme Court.  

With new exhibits in the Courthouse Museum and visitation in Lincoln at an all-time high, the commission began to look beyond just the courthouse and towards additional preservation opportunities in Lincoln. Fulfilling its mission to expand its preservation efforts in Lincoln, the Old Lincoln County Memorial Commission worked with the Museum of New Mexico to purchase and restore several more properties in town. These new acquisitions included the old John Tunstall Store, which they bought, restored, and opened as a second museum in 1957.  The commission also purchased the property on which the old Wortley Hotel had stood before burning down in 1936. With assistance from state funds, the commission rebuilt the hotel, opening to the public in 1960. He and Caroline moved out of the Courthouse curator’s apartment in 1960 into the newly renovated James Brent house, also purchased and preserved by the commission. During the next few years, the commission also acquired the property on which the McSween house originally sat, the Lincoln Pageant Grounds, and Lincoln’s first courthouse building, known locally as the Convento. These activities encouraged the commission and local community members to nominate the town of Lincoln for consideration as a National Historic Landmark—a dream that came to reality on December 19, 1960.