America marks the 150th anniversary of the first transcontinental railroad

A ceremony's been held in the American state of Utah to mark the one-hundred-and-fiftieth anniversary of the transcontinental railroad - the first continuous link across the United States. Among those being honoured were the thousands of Chinese labourers who helped build it. The event took place in the town of Promontory - where the two lines of the railroad finally met. The BBC's Tim Allman reports.