San Martino in Rio is a comune

Comune

In Italy, the comune is the basic administrative division, and may be properly approximated in casual speech by the English word township or municipality.-Importance and function:...

(municipality) in the Province of Reggio Emilia

Province of Reggio Emilia

The Province of Reggio Emilia is one of the eight provinces of the Italian Region of Emilia-Romagna. The capital city, which is the most densely populated comune in the Province, is Reggio Emilia....

 in the Italian

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 region Emilia-Romagna

Emilia-Romagna

Emilia–Romagna is an administrative region of Northern Italy comprising the two historic regions of Emilia and Romagna. The capital is Bologna; it has an area of and about 4.4 million inhabitants....

, located about 50 km northwest of Bologna

Bologna

Bologna is the capital city of Emilia-Romagna, in the Po Valley of Northern Italy. The city lies between the Po River and the Apennine Mountains, more specifically, between the Reno River and the Savena River. Bologna is a lively and cosmopolitan Italian college city, with spectacular history,...

 and about 12 km northeast of Reggio Emilia

Reggio Emilia

Reggio Emilia is an affluent city in northern Italy, in the Emilia-Romagna region. It has about 170,000 inhabitants and is the main comune of the Province of Reggio Emilia....

. As of 31 December 2004, it had a population of 6,990 and an area of 22.6 km².

The municipality of San Martino in Rio contains the frazioni

Frazione

A frazione , in Italy, is the name given in administrative law to a type of territorial subdivision of a comune; for other administrative divisions, see municipio, circoscrizione, quartiere...

(subdivisions, mainly villages and hamlets) Case Culzoni, Case Vellani, Gazzata, Montecatini, Osteriola, Stiolo, and Trignano.

San Martino in Rio borders the following municipalities: Campogalliano

Campogalliano

Campogalliano is a comune in the Province of Modena in the Italian region Emilia-Romagna, located about 45 km northwest of Bologna and about 8 km northwest of Modena...

, Correggio

Correggio, Italy

Correggio is a small town and comune in the Province of Reggio Emilia, in the Emilia-Romagna region of Italy, in the Po valley. As of 2007 Correggio had an estimated population of 23,108....

, Reggio Emilia

Reggio Emilia

Reggio Emilia is an affluent city in northern Italy, in the Emilia-Romagna region. It has about 170,000 inhabitants and is the main comune of the Province of Reggio Emilia....

, Rubiera

Rubiera

Rubiera is a comune in the Province of Reggio Emilia in the Italian region Emilia-Romagna, located on the Via Emilia about 50 km northwest of Bologna and about 13 km southeast of Reggio Emilia.-History:...

.