Chad, flag of; Romania, flag of Encyclopedia Britannica

None of the world’s national flags are as closely matched to each other as these two. Their design and size are almost identical, and only a close examination reveals slight shade differences between the blue, yellow, and red vertical stripes. The two came from totally different backgrounds. The Romanian flag dates from 1861, based on earlier versions with horizontal stripes. The flag of Chad was first hoisted in 1959 after the country had achieved independence from France. Its original design had a green stripe, but it too closely resembled the flag of Mali, so the blue stripe was substituted. Andorra has a similar flag as well, but it is distinguished by its centrally placed coat of arms.