Challis is the largest city in Custer County, Idaho, United States.

On Friday, October 28, 1983, the Borah Peak earthquake occurred at 8:06 am MDT.

The shock measured 6.9 on the moment magnitude scale and had a maximum Mercalli intensity of IX (Violent).

Mackay in particular, about 50 miles (80 km) southeast of Challis, experienced the most severe damage.

Most of these buildings were built from materials such as brick, concrete block, and stone, each varying.

[10] The two fatalities of the earthquake were in Challis; a store front fell on two children walking to school.

[11][12] On Tuesday, March 31, 2020, at 5:52 pm MST, an earthquake measuring 6.5 on the moment magnitude scale occurred, centered 45 miles (72 km) west of Challis.

[15] Challis experiences a semi-arid climate (Köppen climate classification BSk) with cold winters, hot summers, and low precipitation throughout the year.

There were 529 housing units at an average density of 286 per square mile (110.4/km²).

36.6% of all households were made up of individuals, and 15.7% had someone living alone who was 65 years of age or older.

There were 598 housing units at an average density of 323.2 per square mile (124.8/km2).

There were 525 housing units at an average density of 295.0 per square mile (113.9/km2).