Final answer:
Cyrus McCormick marketed the first mechanical push mowing machine, known as the mechanical reaper, revolutionizing agriculture and increasing productivity.
Step-by-step explanation:
The first mechanical push mowing machine was marketed by Cyrus McCormick. He developed the mechanical reaper, which was initially used to harvest grain but later adapted for mowing grass. McCormick made constant improvements to the design and established the McCormick Harvesting Machine Company to meet the growing demand. His invention revolutionized agriculture by increasing productivity and paved the way for further advancements in farm machinery.