First time campers should call Baxter HQ to make their reservations. There is a online rez tool, but I think talking to an experienced and knowledgeable human is a better idea for people new to the Park. Tell them your plans and what vehicle you're bringing. Office hours 8-4 weekdays 207-723-5140

Same goes for first time visitors, go straight to the source for your info!

(Give them a few minutes to fire up the woodstove and put the kettle on in the morning, and call by 3:30 in the afternoon so they have time to close up shop.)