The 99th Division was constituted in Camp Wheeler, Georgia, on July 23, 1918. It was reconstituted as the 99th (Checkerboard) Division and assigned to the Organized Reserve on June 24, 1921. On April 1, 1942, it was reorganized as the 99th Infantry Division.
Following distinguished service in the Second World War, the 99th conducted occupational duties until returning to America and inactivating on Sept. 27, 1945. Reactivated as the 99th U.S. Army Reserve Command on Dec 22, 1967, the 99th has since remained in the Army Reserve. 1975, the 99th ARCOM moved its headquarters to Oakdale, Pa.
After Iraq invaded Kuwait in August 1990, 22 99th units deployed to Saudi Arabia, Europe and other locations. After the Gulf War, the 99th ARCOM became the 99th Regional Support Command (RSC). The 99th RSC’s mission was to provide command and control and full service support for assigned units and facility management.
On Dec. 23, 1996, the 99th RSC mobilized the first of six units for deployment to Operation Joint Endeavor in support of peacekeeping missions in Bosnia. The 99th RSC continued to support operations in the Balkan Republics while providing refuge to those fleeing Kosovo as they sought temporary recovery in the United States.
Following the Sept. 11, 2001, terrorist attacks, the 99th mobilized large numbers of Army Reserve Soldiers. While the 99th was fully involved in this large mobilization, the headquarters moved to Coraopolis, Pa. In January 2003, the 99th RSC started mobilizing units for projected operations in Iraq.
On July 16, 2003, the command was re-designated as the 99th Regional Readiness Command, placing additional emphasis on training, readiness and mobilization. The 99th RRC continued to provide command and control for assigned units and support for the ongoing deployments.
In 2005, the Army Reserve began its latest transformation under the Base Realignment and Closure (BRAC) directive and “lessons learned” from eight years of deployments in support of the Global War on Terrorism. The 10 geographically-based RRCs, including the 99th, were to be inactivated. In their place would be four regional base operations commands. The 99th was selected as one of these new regional support commands.
In September 2007, in preparation for the transition to Fort Dix and establishment of the new 99th RSC, the 99th RRC assumed administrative responsibility for the former regions of the 77th and 94th RRCs, which had inactivated. On September 17, 2008, the 99th Regional Support Command was activated at Fort Dix, N.J.
In late 2017, the four regional support commands were re-designated as readiness divisions. The 99th Readiness Division integrates capabilities with Reserve Commands to provide geographic programs and services that enhance individual and unit readiness, mobilization and deployment of Army Reserve forces.

Information provided by the 99th Readiness Division Historian.

The 99th RD Historian provides support to Army Reserve commanders, units, veterans and the general public in response to historical inquiries, either directly or through consult with the U.S. Army Reserve Command History Office, the Center of Military History, and/or the Army Heritage and Education Center. 

Services include, but are not limited to: 
• Assistance with command organizational history program development 
• Unit and USAR Center artifact collection accountability, conservation, and security 
• Editorial review of command annual history reports
• Oral history interview coordination, including end-of-tour interviews of senior leaders
• Staff ride program planning 
• Military history detachment continuing education and development
• Unit Historical Officer consultation
• USAR Center de-memorialization procedures
• Historical publication acquisition guidance