Countries that have had their current flag for the longest
Can you name the countries that have had their current flag design for the longest period of time
The answers only include current sovereign states, however the state may not have been sovereign at the date of flag adpotion
Disregards changes that do not alter the basic design of the flag; like the changes in ratio or colour shade, restyling of emblems or inscriptions or the addition or removal of stars
I don't think the US flag should be here. While technically the format and idea of the flag design hasn't changed, it went through multiple incarnations as states kept joining.
Of course it should be here. Go back and carefully read the quiz instructions, they say to disregard changes that do not alter the basic design of the flag which includes the addition or removal of stars. As you said the format hasn't changed. The only significant change since 1777 is the addition of stars. The reason why the date listed in the quiz is 1777, is because prior to that the flag featured the union jack which is a different flag design.