Samuel Morse
Before Morse, telegraph systems needed multiple wires—one for each signal—making them costly and impractical. Morse solved this with three breakthroughs. First, he used the Earth as the return path for current, eliminating the need for a second wire. This cut costs and made long-distance telegraphy possible. Second, he invented Morse Code, a simple system of dots and dashes that encoded any message using short and long electrical pulses. Third, he built a reliable electromagnet receiver that clicked or marked each signal as it arrived, allowing operators to “hear” the message. In 1844, Morse sent "What hath God wrought" from Washington to Baltimore over a single copper wire. That moment launched a communication revolution. By combining simplicity, code, and the Earth itself, Morse created a system so scalable that it soon circled the globe—and changed history.