(AP) — Oil pipeline accidents have become increasingly frequent in the U.S. as Congress pushes for approval of the Keystone XL pipeline — a project that would pass near the spot where 30,000 gallons of crude spilled into Montana's Yellowstone River earlier this month. The recent spill temporarily fouled a city's water supply and became the latest in a string of accidents to highlight ongoing problems with maintenance of the nation's 61,000 miles of crude oil pipelines. The number of significant pipeline-related accidents involving crude oil has been growing each year since 2009, reversing a decade-long declining trend, according to an Associated Press review of U.S.