Which countries of the world drive on the left?
For the answer to this question we're going to refer you to What side of the road do they drive on? a comprehensive page on the subject by Brian Lucas
What's great about the site is that Lucas has compiled anecdotes from people around the world to keep the site accurate and entertaining, while the list of countries includes a map of the world that puts into context which countries are "righties" and which are "lefties."
According to a table at the bottom of the page (updated in 2005), 72% of the world's population drives on the right, while 28% drives on the left.
The site answers a lot of questions about the history and decision making that went into making these driving regulations. What role did horse and wagon transportation play? How much did the British Empire influence countries? Did the United States always drive on the right? And why did Sweden switch from the left to the right in 1967? In addition, the site provides first-hand accounts of what it's like to cross over borders between countries that don't share the same rules about which side of the street to drive on.
—The Fact Monster