On January 22, 1865, Mark Twain went north from Jackass Hill, in nearby Tuolumne County, to Angel's Camp with Jim Gillis, who had a claim there. During their first week, heavy rains confined them to Tryon's Hotel; they spent the next three weeks prospecting with little success. Throughout this time -- especially during the rainy week -- Mark Twain exchanged yarns with locals, notably Ben Coon, and left with a notebook filled with story ideas. Chapter 61 of Roughing It briefly describes this period.

Bearmouth was a trading post for the placer mining camps of Beartown, Garnet and Coloma, located in the hills north of Bearmouth in Granite CountyMontana, United States.

Bonita, Montana
Missoula County. Along the Clark Fork River east of Clinton, Bonita was once on the Milwaukee Road and Northern Pacific lines. Two railroad tunnels pass through the Beavertail Hill just east of the former Bonita townsite. The name apparently came from Mexican section hands working on the Northern Pacific tracks in the 1880's; “bonita” is Spanish for “beautiful”. A post office operated in Bonita from 1886 (June 19) to 1942 (August 2). John Lovell served as the first postmaster.

The town of Como was established in late 1862, during the gold rush in Palmyra Mining District.

Mrs. Pond, Clara, Clemens and Major Pond. Crossing the Rockies. The Great Northern. August 9.
Mark Twain Archive, Elmira College courtesy of Kevin Mac Donnell, Austin, Texas.

Major Pond either was mistaken about the location, "crossing the Rockies", or he was unaware that these were the Cascades they were crossing. Twain remarked in his journal that they had stopped a short distance from Wellington and threw rocks down the precipice. Embro is the most likely spot for this.

Founded in 1859 after a gold strike was made south of Mount Davidson.  It became one of Comstock's most prosperous towns while Twain was in Virginia City with a population of about 3,000 people.  By the 1870s, more than 10,000 people lived there, merging with Virginia City.  The area soon declined and is now little more than a ghost town.

Grand Gulf was named for the large whirlpool, (or gulf), formed by the Mississippi River flowing against a large rocky bluff.[2] La Salle and Zadok Cramer commented on the dangers caused by the eddies at Grand Gulf.

Jackass Hill takes its name from mules that clustered around it when it was a pack-train stop.  It became a placer-mining boom town in 1848.  "By the time Clemens arrived there in early December 1864, the camp was a pale shadow of its former glory."  Clemens spend almost three months there with Dick Stoker, Jim and William Gillis, and their cat Tom Quartz.

The Nine Mile Ranch may have held the name of Lone Star Stage prior to ranching operations in the 1800's. According to maps constructed by Holt in 1866 and published more recently in the Book Aurora Ghost City of the Dawn 1996. Evidence supports this theory as the presence of a stone hut remains on site today. Some historians have researched the ranch to have been owned by Captain John Nye, and place Sam Clemens himself here sometime in the late 1800's
http://www.highdesertdrifter.com/ninemile.shtml

Unionville is a small hamlet in Pershing CountyNevada, located south of I-80 and just west of State Route 400 on Unionville Road, with the most recent population estimate being approximately 20 people. The town's best years were during the 1870s, when it was an active mining and prospecting town serving the surrounding hilly region.