Via John Quiggin, here's Matthew Turner in February 2004: "More pertinent for this site perhaps is the exchange rates at which European gdp per capitas overtake those in the Great Republic. For the Europeans it's around euro 1 = $1.46, i.e. they are unlikely to get there anytime soon given we're currently at $1.26." As it happens, the Euro was trading at a bit over $1.46 when I checked a bit earlier.
Now, of course, this isn't actually considered the correct way to do these comparisons -- you're supposed to use the Purchasing Power Parities method which still shows us as richer -- but surely these exchange rates have some significance.
Matthew Yglesias is a former writer and editor at The Atlantic.