What side of the road should you be on when you turn across the median?

This is a question about U.S. driving that I never have been able to figure out. Imagine a four lane road in the city. The two directions of traffic are seperated by a wide median (for streetcar tracks). I am thinking specifically of Commonwealth Avenue in Boston. A commonly required move is to drive across the median in order to make a U-turn and go in the opposite direction. Imagine that the median as a very short two lane bi-directional road. When you turn onto the median, what side of it are you supposed to be on? I always turn onto the right side because that is the direction that you drive on the rest of the time but cars turning onto the median at the same time from the opposite side often try to turn head-on into me on that side (their left, my right). Which way is correct? I admit that turning onto the left side seems a little more efficient.

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Locked since it’s a duplicate thread. The original is in IMHO.

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