Elkhorn Ranch is in the scenic Gallatin Canyon on US 191, 15 miles south of Big Sky, Montana.
If you are driving, coming south from Bozeman or north from West Yellowstone, you will see the ranch on the south side of the highway, opposite the Gallatin River, between mile markers 33 and 34. Coming from the Bozeman, your drive will be an hour to an hour and a half; from West Yellowstone it will be about 40 minutes. From West Yellowstone to the ranch you will be in and out of the Park so watch your speed. Also, in most of the Gallatin Canyon there is no cell reception.
The usual airport is Bozeman Yellowstone International Airport (BZN), known locally as Gallatin Field, and the regional West Yellowstone Airport can work well for some. If you have extra time to spend exploring before your time at the ranch, look into flying into Jackson Hole or Salt Lake City, renting a car and exploring Yellowstone and Teton National Parks, Jackson Hole, maybe Cody, Wyoming. The options are boundless.