OMAHA, Neb. (AP) — A dozen Union Pacific employees will ring the closing bell at the New York Stock Exchange today (Monday), to celebrate the railroad’s 150th birthday. The nation’s largest railroad will also celebrate at its Omaha headquarters on Monday with a bell-ringing reception for its employees. Union Pacific is holding a number of events in 2012 to commemorate the day when President Abraham Lincoln signed the law creating the railroad on July 1st, 1862. The only problem with today’s celebration, is that it is happening one day after the actual anniversary. Union Pacific had to adjust its plans because July 1st falls on a Sunday this year.Union Pacific started laying rail in Council Bluffs, Iowa, and worked westward to meet the Central Pacific railroad. The transcontinental railroad was completed in 1869.