The town was founded in the early 1950’s as part of the development of the Soviet military-industrial establishment. On March 17, 1954, industrial community Zlatoust-36 was established and later transformed in a town. Official date of foundation of Trekhgorny – is April 9, 1952. Until the early 1990s the town was almost entirely closed for the outside communication.

Trekhgorny is situated in the western part of the South Ural between Katav-Ivanovsk and Satka districts, 200 kilometers from Chelyabinsk. The town occupies the area of 16 249 hectares. About 80% of the territory - is woodland.

The population of the town is about 40 000 people. A mean age of the citizens is about 32 years. 55% - are able-bodied citizens, 19% from the total number are the pensioners. For the first time during the last years, improvement of demographic setting and positive natality – 44 people were registered in 2003.

The main enterprise of Trekhgorny is “PRIBOROSTROITELNY ZAVOD”. This plant fulfills designing, producing and complex delivery of products of general technical purpose to enterprises of power complex and atomic energetics.

The main products of the plant are apparatus complexes ARMS-2000, RSMH-08, which are meant for - control of radiation safety of NPP power-generating unit, control of radiation environment of NPP industrial areas, control of radiation environment of radioactive waste storage, control of region radioactive environment.

The enterprise also produces apparatus complexes NFME-7, NFME-7-02 for control of neutron flux. An apparatus complex PDMI, meant for safety and control of reactor facilities; and stationary lead-acid batteries GrOE, OPzS.

At present time, the plant has also started production of pumps meant for milk processing industry, trailers and manufacturing machines.

About 250 enterprises are registered and function in the town. The largest of them are: municipal enterprise “Improvements industrial complex” (road repairs, municipal improvements, etc.), municipal enterprise “Rassvet” (“Dawn”) (woodworking, production of finish and furniture), research-and-production enterprise “Conversion-P” (plating technologies, modernization of manufacturing equipment), research-and-production firm “B-Forum-B” (production of armature for petroleum-refining and gas producing enterprises; production of rectifying columns for petroleum-refining enterprises), “Ron-Telecom” Ltd. (digital Private Automatic Exchanges, digital automatic telephone exchanges, equipment for construction of SDH networks and data transmission networks), “Zarya” OAO (translated into English as “Dusk”) (ready-made garments, working clothes, knits), “Konsum” OAO (production and selling of foodstuffs, mineral water “Kurgazak”).

Close corporations: "Promplita" (Flakeboards FB of usual quality and Homogeneous Flakeboards of average density and high-quality HFB), "Stroykomplektatsia" (shower cabin, automobile boxes, rowing boats, and ceramic latches), "Akvapolimer" (Acrylics baths - simple, with hydromassage and for sanatorium treatment; the laminated parquet), "Trekhgorny Plastic" (Plastic pipes and fittings made of polypropylene, used for installation of systems of cold and hot water supply and industrial pipelines), "Armotex" (glass-grid, thermoplastic reinforced pipes designed for transportation and transmission of liquid, gaseous, neutral and chemically aggressive products), NPO "Forum" (cast artificial stone, metal tile. Goods made of cast artificial stone), "Trekhgorny Ceramic Factory" (the enterprise produces propant - granule material used in gas-and-oil producing industry for increase of efficiency of feedback of boreholes with application of hydro-break technology), "Russian Windows” (steel translucent designs: winter gardens, pavilions, stop stations, warm stained-glass windows and transparent roofs, aluminium designs: entrance groups, doors, sliding balconies and stained-glass windows, elite windows and doors from glued bars, etc.), "Promstroykabel" (power cables, installation wires, auto and tractor wires), "Accumulator" (fixed, closed lead-acid accumulators under the license of "HOPPECKE" company), "EcoMotor" (creation of harmless Internal-Combustion Engines (ICE), petrol power plants, equipment for reinforcement of surfaces of details from aluminium alloys), "UralAlmazInvest" (heat-removing diamond substrates; windows and plates of a wide assortment; profiled diamond products for medicine), "Variant" (pumps, fans, explosion-protected engines, hot-air generators).

Social infrastructure is presented with infant schools, schools of general education, high schools and colleges, a Branch of Moscow Engineering-Physical University, a Branch of South Ural State University, music school, 4 sports schools, children’s ecological center, hospitals and polyclinics, stadiums.

Trekhgorny is also famous for Skiing resort Zavjalikha, which is situated not far from the town. The keystone of the ski complex is the mountain Zavjalikha. In 15 minutes drive from the mountain "Zavjalikha", hotel "Kamenny Tsvetok" ("Stone Flower") is situated. Building of new hotel complex, restaurant network, cafe and car parking is taking place.