Wild and Scenic Rivers System (WSRS) is an important protected area system on the federal level of the United States, and the earliest river protected area in the world. Based on literature and interviews, the history of WSRS development is divided into three phases by landmark events. The great achievements during each stage are summarized and the main influencing factors are analyzed. The results show that the development of WSRS can be divided into three stages: preparation stage, refinement stage, and smooth development stage. The average growth rates during the three stages are 7.3, 6.0 and 3.3 segments/year. During the preparation stage, the concept of river protected area was put forward and the Wild and Scenic Rivers Act (WSRA) was promulgated. During the refinement stage, WSRA was revised further, and the management mechanism was improved. During the smooth development stage, the treatment measures of the federal agencies towards WSRS were further improved. Judging from the whole development process, the ideology of wildness protection is where the WSRS originates; the public needs of recreation is the public foundation for WSRS; the anti-dam movement pushed the development of WSRS; and the governance was the main aspect for improvement in the WSRS. The main factors affecting the development of WSRS include the push by the river protectionists, interactions between the political parties of the federal government, balance between river protection and economic development, and restriction caused by land ownership along the rivers.