Workers stand next to a gas pipeline not far from the central Ukrainian city of Poltava in June 2014. Ukraine imports much of its gas from Russia, which is once again threatening to cut off supplies in a dispute over payments.
Sergei Supinsky/AFP/Getty Images
Drilling rigs dot the landscape near Calumet, Okla., in April 2013. Oklahoma's economy blossomed during the domestic fracking boom, but as the price of crude oil drops, that could change.