According to a little research, there are only four primary passport colours in the world, and each country has its own reasons for choosing one of these colours for the cover. This post lists the colours and their reasons.
- RED
This is the most common colour. Passports with a red cover are often chosen by countries with a historical or current communist system. Citizens of Slovenia, China, Serbia, Russia, Latvia, Romania, Poland, and Georgia have red passports. Member countries of the European Union, except Croatia, also use passports of Burgundy and other shades of red. Countries interested in joining the EU, such as Turkey, Macedonia, and Albania, changed the colour of their passports to red colour a few years ago. The Andean Community of Nations — Bolivia, Colombia, Ecuador, and Peru — also has burgundy passports
- BLUE
This is the next most common colour. The blue cover symbolises the “new world”. 15 Caribbean countries have blue passports. Within the block of South American countries, the blue passport cover symbolises the connection with Mercosur — a trade union. This includes Brazil, Argentina, and Paraguay. Venezuela is the exception here: it also belongs to the union, but its citizens have red passports. The passports of US citizens were changed to blue only in 1976.
- BLACK
The rarest passports are those with black covers. These can be found among the citizens of some African countries — Botswana, Zambia, Burundi, Gabon, Angola, Chad, Congo, Malawi and others. Citizens of New Zealand also have black passport covers, because black is the country’s national colour.
- GREEN
Most Muslim countries have green passports. Examples include Morocco, Saudi Arabia, and Pakistan. Green is considered to be the favourite colour of the Prophet Muhammad and is a symbol of nature and life. The citizens of several West African countries — for example, Burkina Faso, Nigeria, Niger, the Ivory Coast, and Senegal — also have travel documents that are various shades of green. In their case, the colour indicates that they belong to ECOWAS (the Economic Community of West African States).