Emerging and Frontier markets are still the lowest cost labor markets. According to research from JP Morgan Asset Management:
Wages, which are the largest part of most manufacturers costs, are still vastly different around the world, regardless of the rise in manufacturing costs in some emerging market countries seen over the last decade.
Here is a great graph from JP Morgan depicting this data:
Today, manufacturing labor from China is 10 times lower that the U.S. However the gap is closing since in 2001 the gap was significantly higher at 39 times.