Regional power

In international relations since the late 20th century, a regional power is a term used for a state that has power within a geographic region. States which wield unrivalled power and influence within a region of the world possess regional hegemony.
Characteristics.
Regional powers shape the polarity of a regional area. Typically, regional powers have capabilities which are important in the region but do not have capabilities at a global scale. Slightly contrasting definitions differ as to what makes a regional power. The European Consortium for Political Research defines a regional power as: 
"A state belonging to a geographically defined region, dominating this region in economic and military terms, able to exercise hegemonic influence in the region and considerable influence on the world scale, willing to make use of power resources and recognized or even accepted as the regional leader by its neighbours".
The German Institute of Global and Area Studies states that a regional power must:
Regional powers.
Below are states that have been described as regional powers by international relations and political science academics, analysts, or other experts. These states to some extent meet the criteria to have regional power status, as described above. Different experts have differing views on exactly which states are regional powers. States are arranged by their region and in alphabetic order.
North America.
Canada, despite being a middle power, is not a regional power because it is militarily secured by U.S. hegemony and financially comfortable by its dependence on a robust U.S. economy. The United States is the primary geopolitical force in North America, and is considered the sole superpower at the moment. In fact, its projection of power is so large that Canada and Mexico, both middle powers are generally not considered regional powers. The case of Mexico is a strange one due to this scenario, where it is not considered a regional power if grouped with North America, but is considered a probable regional power if grouped with Latin America and a definite regional power if considered in either Central America or in Spanish-speaking America. 
South America.
In the past, Spain and Portugal were the dominant powers in the region but following decolonization in the first half of the 19th century, the major powers became Brazil and Argentina.
Asia.
Historically, China was the dominant power in East Asia. But, at the beginning of the early 20th century, the Empire of Japan became the dominant force of Asia in World War I as one of the Allied powers. With economic turmoil, Japan's expulsion from the League of Nations, and its interest in expansion on the mainland, Japan became one of the three main Axis powers in World War II.
Since the late 20th century, regional alliances, economic progress, and contrasting military power have changed the strategic and regional power balance in Asia. In recent years, a re-balancing of military and economic power among countries such as China and India has resulted in significant changes in the geopolitics of Asia. China and Japan have also gained greater influence over regions outside Asia, with the former now contending with the United States for geopolitical clout in most major regions. With close economic and military ties to the United States, Japan was the main Asian base of operations of America's "containment" strategy during the Cold War. In recent decades, South Korea has emerged as a significant economic and cultural force in East Asia, while Indonesia has solidified its place as the economic heavyweight of Southeast Asia.
Europe.
Russia – considered a potential superpower, is a major great power and has historically been the primary geopolitical force in Eastern Europe, while France, Germany, Italy and the United Kingdom are seen as the Big Four of Western Europe. Historically, dominant powers in this region created large colonial empires worldwide (such as the British, French, Spanish, Portuguese, Italian, German, Russian and Dutch empires). Most of the continent is now integrated as a consequence of the enlargement of the European Union.
Oceania.
Australia is considered to be a regional power due to its power relative to the nations around it. For instance, despite having less than a tenth of Indonesia's population, Australia has a larger GDP (nominal). Despite not possessing a particularly large military in terms of manpower, Australia's military expenditure is the 11th highest in the world and is considerably higher than any other nation in the region, giving it a major military advantage.