The shot that grazed Donald Trump’s ear is just another reminder of how the United States, unique among the dominant English-speaking countries, remains subject to both actual violence and threats of violence. Over the past two centuries, four American presidents have been killed, and there have been numerous attempts, most recently on Ronald Reagan.

In contrast, only one British prime minister has been assassinated. Not a single Canadian or Australian leader has been killed, although one Aussie prime minister, Harold Holt, disappeared in 1967; many think he drowned in a swimming accident, although some also see political conspiracies. Political violence, of course, occurs in all these countries, but not anything like what we see in the United States.

Why is this? One has to start with the country’s origins. The United States is the only British colony with a predominately Anglo population to break violently from the mother country. Canada, Australia and, of course, the United Kingdom’s political systems have a history of accommodation, with the Crown gradually ceding power to the colonies as well as the British commoners. Continuity, as epitomized by the Royal family, has its advantages.

America, on the other hand, was a revolutionary state and appealed to an independent spirit that, at times, lurched into violence. Compared to other British offshoots, Americans tend to resist control, even when it may be useful, as in the case of guns. America is also a military superpower and has a long history of engaging in warfare well beyond its borders. Unlike Britain, which is no longer an empire, nor any of its other offshoots, the U.S. remains a dominant global force.

To be sure, Canada and Australia control larger land masses, but the U.S. is by far the largest anglophone country (unless you include India, where many speak English as a second language). Its population of over 330 million is almost three times as large as the combined inhabitants of Canada, Australia and the United Kingdom. Its size and diversity create a naturally complex, and combative, political culture.

Federalism, a critical part of the U.S. Constitution, is designed to accommodate regional differences in a way that’s not as evident today in Britain and Australia, and increasingly Canada, despite the unique status of Quebec. In the U.S., different states and regions can maintain very different political economies and cultures. A large part of the country, the south as well as Texas, were once independent countries, and fought bitterly to retain their independence. This part of the country — which is becoming increasingly dominant, both demographically and economically — forms the base of support for Trump and the GOP.

These divides, and the country’s rebellious roots, help explain some of its increasingly vicious political culture. Canadians, Australians and Brits may have their heated squabbles, but in the U.S., the divides are sharper. This can be seen by the attempts on both sides to blame the assassination attempt on the rhetoric of the other side.

Read the rest of this piece at National Post.

Joel Kotkin is the author of The Coming of Neo-Feudalism: A Warning to the Global Middle Class. He is the Roger Hobbs Presidential Fellow in Urban Futures at Chapman University and and directs the Center for Demographics and Policy there. Learn more at joelkotkin.com and follow him on Twitter @joelkotkin.