The Spaniard, who was close to joining the Red Devils last summer, eventually agreed a deal at Old Trafford in June.
He is likely to appear in a red shirt for the first time in America later this month when United face the likes of Real Madrid and Inter Milan in pre-season friendly encounters.
"I'm really excited to go with United to America. We will play some big games against Roma, Inter Milan and Real Madrid. It will be a dream for me to pull on the United shirt against them," Herrera told MUTV.
United's tour will begin with a match against LA Galaxy on July 23.