In 1844 Morse has just run his test line from Baltimore to DC. Ezra Cornell was involved because he'd invented a trench digger and they both thought telegraph wires could be run under ground. They were 20 years too early for plastic insulation so that went pretty poorly. The first commercial telegraph line was run from Washington, DC, to New York City in 1846 by the Magnetic Telegraph Company
In 1849, Sibley joined with Selden and to start the New York State Printing Telegraph Company (NYSPTC) armed with Selden's Morse patents. There were competing systems, so if Selden had a license from Alexander Bain this could be a very different tale. Regardless, telegraph companies didn't have exclusive licenses, or they were poorly executed. NYMVPTC was competing with telegraph companies in New York, Albany, and Buffalo. Selden and Sibley handled this by buying up several of them and consolidated them into The New York and Mississippi Valley Printing Telegraph Company (NYMVPTC.) This was good for business so they went on to purchase all the companies west of Buffalo. This didn't just increase their market share, it also eliminated competing telegraph standards.
But there were still rival systems in the West. There were at least a dozen separate companies using at least 2 different non-Morse systems. NYMVPTC ultimately purchased and converted them too. In 1854 Sibley bought the Morse licenses for the whole Midwest for $50,000 from Jeptha H. Wade, who became a board member. His properties includes lines to Michigan, Chicago St. Louis, and Nashville. He also bought the St. Louis and Salt lake City telegraph company from John J. Speed. Sibley manage to do all of this without the knowledge of his competitor Ezra Cornell. Cornell owned the Erie and Michigan Telegraph Company (EMTC). His lines stretched out to Detroit, Indiana and Illinois. More here and here.
Eventually Ezra Cornell was brought into the fold. NYMVPTC bought EMTC from Cornell in 1855. In 1856, the company name was changed to the "Western Union Telegraph Company." Ezra Cornell went on to found Cornell University in 1865—currently the home of 93.5 WVBR. All's well that ends well.