All these three great men invented machines that completely changed the societies they lived in. However, in my opinion, Samuel Morse probably had the largest impact on the nation's development.
Both John Deere and Cyrus McCormick invented intelligent machines such as harvesters that were able to considerably lower the need for labor and improved agricultural output.
The machines contributed to larger plantations and surplus crops which made the United States self-sufficient and eventually become a major exporter.
However, Samuel Morse was the investor of the single-wire telegram. One of the earliest forms quick communication over hundreds of miles, the invention was able to provide a new vision to how humans could communicate.
It brought the nation closer, improved connectivity, helped created a basic technological infrastructure and fulled innovation and entrepreneurship in the country that still survives today.