This meticulously researched master's thesis from a student at the Naval Postgraduate School, published in December 2019 and written prior to the formal establishment of United States Space Force, provides a thorough historical review of how the three major U.S. military branches--Army, Navy, and Air Force--have handled their responsibilities in the space domain. The author observes in his Abstract: The concept of a "Space Force" has been debated in rooms at the Pentagon, on social media, and even as a potential series on Netflix, yet space operations have been an integral part of the U.S. armed forces for about 40 years. U.S. interest in space began as an urgent move to prove our nation's competitiveness during the Cold War. Today, the initiative to have a Space Force is rooted in the nationalism of President Donald Trump. The Space Policy Directive-4 signed by Trump is waiting for congressional approval, so a historical review of the role of space within the U.S. military is needed. This thesis analyzes the roles the Army, Air Force, and Navy have already played within the combined space effort. Through this historical analysis, this study offers a comparative examination of the space interests of each of the three branches of service, showing how each defines and views space, and addresses space organization within the services. The study concludes that the Air Force Space Command should remain under the U.S. Air Force and be renamed the Space Corps with both United States Space Command and the Space Corps being the central chain of command for all the services. While the author's view did not prevail under the Trump Administration, the election of President Biden may reopen The Great Space Race Debate, making this author's research of continuing relevance. Five chapters, 355 footnotes, bibliography.