The Signal Corps in the twenty-first century bears little resemblance to the organization founded by Maj. Albert J. Myer in 1860. Although the United States Army was the first in the world to have a separate communications branch, the legislation authorizing its establishment provided for neither permanent personnel nor units. Soldiers were detailed to signal duty from their regularly assigned units. During the Civil War small signal parties served with the various military departments, but they were disbanded at the end of the conflict. For the next thirty years, the Signal Corps remained a small organization whose members were scattered among the Army's many posts to provide communications and take weather observations. The necessity for having a separate Signal Corps continued to be debated in the halls of Congress and within the Army itself. Communications still was not widely recognized as a military specialty in and of itself. The earliest permanent signal units were formed in the National Guard during the 1880s. New York and Illinois were among the first states to have such organizations. It took the Regular Army a little longer to follow suit. Signal companies designated A through H entered the force structure in 1898 and 1899. From this modest start, the Signal Corps continued to grow during the twentieth century as the United States and its Army assumed global responsibilities. The rise of telecommunications also meant that signaling duties became increasingly complex and an integral part of military operations. Today, the Signal Corps consists of approximately sixty-eight thousand men and women. Moreover, information dominance in the form of superior communications is considered to be sine qua non to modern warfare. The Signal Corps has indeed come a long way from Major Myer's original one-man branch. The purpose of this volume is to present in compact form official organizational history information for Signal Corps units. That the Army requires effective communications in an era known as the Information Age is axiomatic. Established in 1860 with the appointment of the first signal officer, the Signal Corps has had permanently organized units since late in the nineteenth century. Their growth in size and numbers over time highlights the increasingly specialized nature of warfare and the rise of sophisticated communications technology.