Alleghany – The town developed from the mining camps of Smith's Flat, Cumberland and Wet Ravine. In 1853, a group of miners from the Allegheny Pennsylvania mine officially designated their communities as the town of Alleghany. Note that they spelled it with an "a" rather than an "e". In its early years, it was also called Alleghanytown or Jericho. In November 1957, a post office was established and the town's name of Alleghany became official. The town's population hit a high of 2,116 in 1860 and then went into a steady decline. Today's population is 85. Alleghany is easily found on most roadmaps in the southwestern part of the county.

Calpine – The town was founded by the Davies-Johnson Lumber Company in the 1920s. Part of it also went by the name of McAlpine. Calpine is easily found on most roadmaps in the northern part of Sierra Valley, just west of Loyalton.

Crystal Peak – From the Daily Nevada State Journal, Reno, Nevada, Thursday, January 21, 1875, Page 3: “A correspondent of the Downieville Messenger sends that paper some news of interest of Crystal Peak, which we reproduce here: Crystal Peak is situated at the foot of the bill and on the State line, all of the property, however, being in  California.  Several years ago it was quite a place, and, but for the timber interests, would now be defunct.  It has one hotel, kept by James Carson, and formerly had two stores and a post office, but these are now removed, Verdi, on the R.R., a half mile distant, being the objective point.  W. D. Coldren, formerly a partner of Wm. Stoddert, in Downieville, had a store here for several years.  Mr. Coldren is now a short distance above Crystal Peak on the Truckee River (But in the State of Nevada) engaged in the wood business. The whisky business holds out to the last, and Crystal Peak has two saloons and a brewery kept by Messrs. Carson, Foxwell and Grazier, respectively.  Mr. Grazier’s beer enjoys a great reputation and is shipped to distant parts on the railroad.  South of town and within a mile are two fine little ranches owned by S.  L. Lawton and Philip Judkins. J. B. Gillhem runs the blacksmith shop and W. E. Squires the shoe making business. Archibald McAfee is Justice of the Peace of the township and James Sproul Constable.  Mr. Sproul is a very pleasant and accommodating gentleman, and any business entrusted to his care will be well attended to.  Southwest of the town is a saw-mill, built in 1864, now owned by Foulks & Rhodes.  They cut last season 800,000 feet of lumber.  The timber claims in that vicinity are nearly all taken up and rapidly being cut off to supply the Nevada market with wood.  In a few years when these vast forest are gone there will be but little left to keep people in the town.  Crystal Peak was formerly, while the laws of Nevada permitted, the Gretna Green of Sierra County, and many of our runaway couples were made happy within its precincts by its accommodating justice.  Several years ago, while on this Rev. Mr. Hinckle informed me that he put out, at Crystal Peak, the first grape in the then State of Nevada.”

Goodyears Bar – During 1849 to 1856, miners found large quantities of gold in sand bars (each called a bar) that were created by merger of two rivers or streams. The town of Goodyears Bar is located where Rock Creek, Woodruff Creek and Goodyear's Creek merge with the North Yuba River. It was founded by brothers Miles and Andrew Goodyear. Intensive sand bar mining took place here for several years. Goodyears Bar is easily found on most roadmaps, located just west of Downieville.

Loyalton – In the 1850s, settlers moved into the area around Smithneck Creek. In 1867, the town successfully petitioned the federal government for the establishment of a post office in the town under the name of Loyalton (name reflects the town's steadfast support for the Union during the Civil War). The town incorporated in 1901. Loyalton is located in the northeastern part of the county. This is the only large area in the county where cell phones work. Cell phone reception is also possible from some mountain tops.

Old Mountain House – Also called Mountain House. A lodge at the top of a mountain along the road (west side) between Alleghany and Goodyears Bar. It operated as a stage stop and later, an auto stopover, for traffic traveling north to Downieville. It was abandoned soon after Highway 49 opened. In the 1970s, the Forest Service demolished the building and locals reused some of its material. Parts of Old Mountain House survive today as part of the St. Charles Hotel in Goodyears Bar.

Sattley – Has a small number of residents, many of whom are descendants of the first settlers in that portion of Sierra Valley.

Sierra Valley – It is the largest alpine valley in the U.S. where the towns of Loyalton, Sierraville, and Sattley are still today, not to mention the towns on the Plumas County side of the valley.