Final answer:
Vanderbilt consolidated smaller railroad lines into the New York Central Railroad Company and purchased stock in major lines to create an efficient network, which increased his control and wealth.
Step-by-step explanation:
Commodore Cornelius Vanderbilt gained control of all his rival railroads through the strategic consolidation of smaller railroad lines, creating the New York Central Railroad Company. This action transformed it into one of the largest corporations in the United States at that time.
By buying stock in the major rail lines that connected to Chicago, Vanderbilt created an efficient railroad network that connected Chicago to New York City and allowed for more effective connections from Midwestern suppliers to eastern markets. His methods of railroad consolidation led to his immense wealth and power in the railway industry.