There are two basic historical roots of centrist politics.
First were the center parties that emerged initially in Europe, and subsequently spread alongside the adoption of democratic government in countries around the world.
Center parties arose in multi-party parliamentary democracies as an effort to find a middle position between parties to the left and right. Typically, they adopt some views from parties to the left and some from parties to the right, while actively opposing what they see as the more extreme views of each side.
Some center parties associate themselves with the tradition of classical liberalism, which emphasizes personal and economic liberty. Many adopt a mix of views drawn from the right on economic matters and the left on social or cultural matters. Thus, some adopt a mixed politics combining market economics, on the one hand, with a focus on social tolerance, inclusion, and protecting the environment.
Center parties emerged worldwide with the spread of democracy through Latin America, Asia, and Eastern Europe. Most parliamentary democracies have a party that positions itself between left and right.
The second centrist tradition emerged more recently in the United States.
Its early roots were in a reform movement within the Democratic party. Centrist Democrats established the Democratic Leadership Council and attempted to change certain traditional party views.
They achieved the most dramatic early electoral success when former DLC chairman Bill Clinton became president in 1992.
As president, Clinton implemented two policies that dramatically illustrated a change in direction. He embraced economic globalization through free trade policies, and he signed a welfare reform bill that dramatically rolled back a major entitlement program.
Centrism subsequently became a bipartisan phenomenon as moderate Republicans began to gather in groups like the Republican Main Street Partnership, and to advocate an emerging centrist politics of fiscal responsibility combined with social tolerance.
The popularity of Clinton's centrist style and easy reelection in 1996 became an inspiration and catalyst for center-left parties in Europe, presaging the rise in 1997 of Tony Blair and the New Labor party in Britain, and in 1998 of Gerhard Shroeder in Germany.
Centrist Democrats in the U.S. and center-left parties in Europe have shared ideas and adopted a new basic philosophy that emphasizes competitive enterprise, fiscal discipline, and individual empowerment rather than a reliance on redistributive entitlement programs.
Meanwhile, centrist Republicans in the U.S. have embraced traditionally left cultural policies, while maintaining their conservative tradition on economic and fiscal issues.
In essence, centrism has emerged as a political movement with two prominent features. First, an effort to adopt a middle position on the traditional left-right spectrum. And second, a tendency to combine some of the traditional economic and fiscal views of the right with the social or cultural views of the left.