Congenital anomalies are also known as birth defects, congenital disorders or congenital malformations. Congenital anomalies can be defined as structural or functional anomalies (e.g. metabolic disorders) that occur during intrauterine life and can be identified prenatally, at birth or later in life.
But unlike in 2012 when Wyoming was home to nine of the US' ten biggest coal mines, the Cowboy State had a bit more competition last year. North Dakota's Freedom mine has taken the spot of the US' tenth biggest coal producer, as Wyoming's Caballo slid off the top-ten chart. All production figures are in metric tonnes.
In 2013, there were 80,209 people employed in coal mining in the U.S. Of those, 47,475 worked in underground mining, and 35,398 worked in surface mining. Here is a breakdown of the geographical distribution of underground coal mining jobs in 2006 (with coal production in thousands of short tons):