WASHINGTON -- Landmark legislation to curb U.S. greenhouse-gas emissions was approved by the House of Representatives in a close vote late Friday, securing an initial victory for a cornerstone of President Barack Obama's agenda.

The 1,200 page bill -- formally known as the "American Clean Energy and Security Act" -- will reach into almost every corner of the U.S. economy. By putting a price on emissions of greenhouse gases, such as carbon dioxide, the bill would affect the way electricity is generated, how homes and offices...