Conservatism as we know it today did not really exist before the twentieth century. Prior to that, it was just the way things were done.
Conservatism really began to develop as a political force in the wake of the New Deal, which effectively inverted the constitutional schema. Previously, the federal government was only allowed to do what the Constitution expressly authorized. From the New Deal onwards, the government could more or less do anything that the Constitution did not expressly forbid. This inversion gave birth to the conservative movement.
Eventually, American conservatism found a home in the Republican Party, where it now almost exclusively resides. But the GOP predates the conservative movement by nearly a century, and has long been home to a very different political tradition.
Full text at: http://thefederalist.com/2015/02/11/the-republican-party-is-not-your-friend/