You will need a ticket to access Lake McDonald, The Going to the Sun Road, and Bowman Lake (IN ADDITION to a park pass) if you enter between the hours of 6am and 5 pm from Memorial day through Labor day. There are long lines to enter starting at 5 pm, even 5:30 seems to be a better time. The ticket can be purchased 60 days in advance, or 2 days in advance when a smaller number are released. Your best shot is getting the ticket 2 months in advance, sitting on your computer with an account already created at recreation.com at 8 AM Mountain, that’s 7 AM Pacific, 9 AM Central and 10 AM Eastern.
The ticket is valid for entry for 7 days. If you have a reservation somewhere along Going to the Sun Road you will automatically be allowed access to the park, though this is only valid for the day of the reservation.
For example: Let’s say you need access to Going to the Sun road on July 25th. You could reserve a ticket for that day on May 26th, or you could reserve a ticket on July 23rd. Because the ticket is valid for 7 days, you also could get a ticket for July 18th, and that way your ticket is valid for the day you need it. Use the link below to buy a ticket, they go on sale starting at 8 am MST
You only need a ticket to enter the park at West Glacier, St. Mary, and Polebridge. The Two Medicine and Many Glacier entrances do not require a ticket, only a park pass.
https://www.nps.gov/glac/planyourvisit/gtsrticketedentry.htm
