| Province of Terni | |
| Settlement Type: | Province |
| Subdivision Type: | Country |
| Subdivision Name: |  Italy |
| Subdivision Type1: | Region |
| Subdivision Name1: | Umbria |
| Seat Type: | Capital(s) |
| Seat: | Terni |
| Parts Type: | Comuni |
| Parts Style: | para |
| P1: | 33 |
| Leader Title: | President |
| Leader Name: | Gianpiero Lattanzi |
| Unit Pref: | Metric |
| Area Total Km2: | 2122 |
| Population Total: | 228236 |
| Population As Of: | 28 February 2016 |
| Population Density Km2: | auto |
| Demographics Type2: | GDP |
| Demographics2 Footnotes: | [1] |
| Demographics2 Title1: | Total |
| Demographics2 Info1: | €5.030 billion (2015) |
| Demographics2 Title2: | Per capita |
| Demographics2 Info2: | €21,885 (2015) |
| Timezone1: | CET |
| Utc Offset1: | +1 |
| Timezone1 Dst: | CEST |
| Utc Offset1 Dst: | +2 |
| Postal Code Type: | Postal code |
| Postal Code: | 05010-05018, 05020-05026, 05028-05032, 05034-05035, 05039, 05100 |
| Area Code Type: | Telephone prefix |
| Area Code: | 075, 0744, 0763 |
| Registration Plate: | TR |
| Blank Name Sec1: | ISTAT |
| Blank Info Sec1: | 055 |
The province of Terni (it|provincia di Terni) is the smaller of the two provinces in the Umbria region of Italy, comprising one-third of both the area and population of the region. Its capital is the city of Terni. The province came into being in 1927, when it was carved out of the original unitary province of Umbria.
The province of Terni has an area of 2,122 km2 and a population of 228,836 (2016). There are 33 comuni (: comune) in the province.[2]
In June 2006, the only comuni (municipalities) with a population over 10,000 were Terni, Orvieto, Narni and Amelia.
It is bordered to the north with the province of Perugia, to the east, south and west with the Lazio (province of Rieti and province of Viterbo) and to north-west with the Tuscany (province of Siena). The province extends into the south-west of the Umbria region, occupying the last section of the Nera Valley near the confluence with the River Velino, and the eastern part of the valley of the Tiber Valley.
The province of Terni is characterized by its slopes encountered along the path of rivers, allowing the exploitation of hydro catchment areas, so as to have led to the creation of several artificial lakes:
In the 2nd millennium BC the province was occupied by a population called Umbri, who founded the cities of Amelia, Narnia Nahars, Otricolum and Interamna Nahars. With the development of the Etruscan civilization, their territory was reduced to the valleys of the Black and Velino. One of the most important and richest Etruscan cities in province of Terni was Orvieto and an unidentified place called Fanum Voltumnae. For centuries, Umbrian and Etruscan fought hard for the rule of the Tiber Valley, until, in 299 BC when Roman legions began the invasion of Umbria.
The provincial territory was part of the Roman Republic and then the Roman Empire until the latter's western part fell in the 5th century AD. In 571 the Lombards, after invading the Po Plain, went down the Apennines and, in 575, founded the Duchy of Spoleto in what is now Umbria and the neighbouring areas; this state remained formally independent until 1250. In 1527 Terni was used a camp of the Landsknecht army that would subsequently take part in the Sack of Rome and fought at Spoleto and Todi, where the League of Cognac troops were located.
Before the late-19th century industrial development, Terni was a small center with some 15,000 inhabitants in 1881. In 1921 it had grown to 40,000 inhabitants. In 1926 it became the seat of a separate province, detached from Perugia, including the countryside around the main centres of Terni and Orvieto.