What we now call electronic privacy first became an issue in the eighteen-seventies, after Western Union, the earliest and, in some ways, the most terrifying of the communications monopolies, achieved dominion over the telegraph system. Western Union was accused of intercepting and reading its customers’ telegraphs for both political and financial purposes (what’s now considered insider trading). Western Union was a known ally of the Republican Party, but the Democrats of the day had no choice but to use its wires, which put them at a disadvantage; for example, Republicans won the contested election of 1876 thanks in part to an intercepted telegraph. The extent of Western Union’s actions might never be entirely known, since in response to a congressional inquiry the company destroyed most of its relevant records.
via Why Monopolies Make Government Spying Easier : The New Yorker.