Late 18th century. The chaos of the French Revolution arguably diluted its viability as an example to other countries, despite the structure of democratic government being objectively better, so you can argue that we were still on the cutting-edge through the 19th century, even, when most countries were still autocracies or constitutional monarchies with extremely questionable de jure voting systems.

I would argue as late as the 1950s, our democratic structure was closer to average than below-average, but by the 1970s, what gave the US more in-common with other developed democracies was that we had extensive practice with our democratic system; by then our structure was not just hopelessly outdated, but a structure that no one in their right mind would take seriously as a foundation for a new government. Come the fall of most of the single-party Soviet-backed regimes of the 1990s, and the only countries we actually beat out for being a ‘good democracy’ are ones that… well, are only questionably democracies to begin with. And even then, most of them have structures that are superior to our’s; only a tradition of civic participation has led us to hobble on as long as we have without becoming an outright authoritarian state.

Though this might be the last month I can say that, which says a lot about the failures of our shitshow of an attempt at implementing democracy.