It's hard to tell, even on the original, but based on the print date of June 1912, and the letter's date of October 1913, it is the Southern Pacific name that has been blanked out.
Print date September 1910; letter date December 1911.
Print date December 1909; letter date September 1910.
Print date June 1909; letter date June 1910.
Print date November 1904; letter date March 1905.
Print date August 1906; letter date November 1907.
Print date December 1907; letter date February 1908.
No print date; letter date February 1906.