The company limited its activities to Pennsylvania until deregulation of electrical utilities in the 1990s encouraged PPL to purchase assets in other states. The largest of these transactions was PPL's 1998 purchase of 13 plants from Montana Power (leaving NorthWestern Energy – the buyer of the former Montana Power transmission and distribution systems – vulnerable to high "spot" prices on the energy market). This added over 2,500 MW of capacity and was the largest expansion in PPL's history. In 2014, those hydroelectric facilities were sold to NorthWestern.