UPDATE: As of February 2014, US 93 has one round trip per day. I-15 will have one round trip per day between Great Falls, Helena, and Butte starting February 20th..
ORIGINAL POST: Salt Lake Express just announced that, effective August 21st, they will be cancelling Route SLE0073 and SLE0074 from Great Falls, MT to Butte, MT on I-15.
Until someone steps in to fill the service, this means Helena and Great Falls will have no intercity service. The only intercity service in Montana will be on I-90 and I-94.
Montana and North Dakota Intercity Bus Status 
I need some help as I need a bus schedule and fare from any website as I’m seeking a bus ride from Missoula to Helena (hoping to make a day trip).
Your help is much appreciated.
Thanks. Gary
It won’t be possible with a day trip, and after August 21 it won’t be possible at all. You can get the schedule from Greyhound.com, but it doesn’t look good. The trip takes 8 hours, 50 minutes, compared to 3 hours by car.
You can buy a ticket at the Missoula bus depot, which is probably the best bet, or through Greyhound, Jefferson LInes, or Salt Lake Express. It’s listed on Greyhound at $37 for travel tomorrow.
Here is the schedule:
Start in MISSOULA, MT 11:15 AM (Jefferson)
Arrive in BUTTE, MT 01:05 PM
Depart BUTTE, MT 06:45 PM (Salt Lake Express)
Arrive HELENA, MT 08:05 PM