"Tues. Evening. We were all uptown until 11:30. Did not get lost." Hard to tell if Grandma is referring to being uptown the previous evening or that morning. Either way it probably wasn't very reassuring to her mother to get such a card.
Mary mentioned in a previous comment that Grandma told her "she graduated from HS one year, married the next and gave birth to Aunt Mary the next year! So if that was the case, this was not her graduation trip. Since we know that Aunt Mary was born in 1913, the marriage was in 1912, that would mean she graduated from High School in 1911. Wish we knew who else was on this trip with her? Did she have a chaperone? (Uncle Ira?)
I'm not sure travel was all that difficult then because of it being the golden age of train service. As long as you were going the same place the train was going!