220799
He participated in the hammering of the Golden Spike that officially joined the Central Pacific and Union Pacific railroads on May 10 , 1869 at Promontory , Utah .
 Central Pacific, Union Pacific, Promontory, Utah
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Central Pacific, Union Pacific, Promontory, Utah