My passport is navy blue. My family members' passports from other countries are a deep forest green, maroon or navy blue also. Thinking about it now, I don't think I've ever seen, say, a hot pink passport. It turns out there's a good reason for that, but it isn't what you think.
Image by seantoyer.
According to Travel + Leisure, there's actually no official rule that says a country's passport must be a certain colour, even though all passports seem to be black or a shade of blue, green or red. If all of a sudden the Australian passport went from navy blue to maroon, that would apparently be a-OK, as long as the paper material can bend, withstand temperatures between 14 and 122 degrees Fahrenheit, and be readable in up to 95 per cent humidity.
But while there are no hard rules that govern the colour, there are practical reasons for darker hues: They make the passport more "official-looking" and better mask dirt marks and other imperfections from regular wear and tear. Additionally, Travel + Leisure points out:
...geopolitics and religion certainly come into play when a country determines the colour of their passport. Muslim countries, for example, largely prefer green passports, because the hue is so significant to the religion. And Caribbean states typically opt for blue passport covers.
And now you can share this delightful bit of trivia with your fellow passengers while waiting to get through immigration.