Of the rest of the land, 34.8% is settled (buildings or roads) and the remainder (5.4%) is non-productive (rivers or lakes).

The blazon of the municipal coat of arms is Argent a Grape Azure slipped palewise and leaved Vert.

Of the foreign population, (as of 2000[update]), 83 are from Germany, 280 are from Italy, 1,028 are from ex-Yugoslavia, 235 are from Austria, 170 are from Turkey, and 197 are from another country.

[7] The age distribution, as of 2000[update], in St. Margrethen is; 612 children or 11.6% of the population are between 0 and 9 years old and 724 teenagers or 13.7% are between 10 and 19.

[3] Out of the total population in St. Margrethen, as of 2000[update], the highest education level completed by 1,336 people (25.3% of the population) was Primary, while 1,822 (34.5%) have completed their secondary education, 354 (6.7%) have attended a Tertiary school, and 311 (5.9%) are not in school.

[10] From the 2000 census[update], 2,138 or 40.5% are Roman Catholic, while 1,406 or 26.6% belonged to the Swiss Reformed Church.

[7] The Old Church of St. Margaretha is listed as a Swiss heritage site of national significance.

[11] Additionally, the Schlosslandschaft Rorschach / Alter Rhein, a number of castles in a region along the Rhine river, is designated as part of the Inventory of Swiss Heritage Sites.

The Schlosslandschaft is shared between Berg, Goldach, Mörschwil, Rheineck, Rorschacherberg, St. Margrethen, Steinach, Thal and Tübach.