USA - oldest nation on earth?

Paul Halsall, whose blog I mentioned in the last post, often has as a foreigner and iconoclast something interesting to say about the United States. Here is one of them, in response to a post on Mediev-L about Americans having such short historical perspectives;

I have to say that in terms of the "political present", Americans have a much lengthier sense than the British.

While one might cite Churchill or Attlee (more likely Beveridge), Harold Wilson, or Margaret Thatcher in a political discussion in modern Britain, I don't think anyone would cite as authoritative the opinions of Baldwin or Asquith, never mind the Duke of Wellington or Pitt the Younger. Occasionally, I suppose, the opinions of past political thinkers might be cited, but not without the awareness of a vast difference between when Locke, Smith, and co. lived and the present.

But American political discussion - this in a modern industrial continental world power - is obsessed with the opinions and ideal of rural politicians of the late 18th- and 19th- centuries, and such ideas are frequently (even if partially or anachronistically understood) put forward as positive support for a position. In a sense the American "political present" stretches well over 200 years, while in Britain it is 60 years at the most.

A comparable phenomenon is the American insistence that the United States is a young country. In fact, there are good grounds for considering it the oldest in the world. Every other part of the world has been conquered or gone through a revolution of some kind which has meant that the modern state occupying any given territory is less old than the USA. I suppose the UK might be considered older, but a) the current "United Kingdom" dates from 1801 (or perhaps 1927 when "UKGBNI" became the name of the state), and b) (more importantly), the series of constitutional, legal/judicial, and administrative reforms of the 19th century created a very different constitution.