Question: Horn is a municipality in the district of Arbon in the canton of what and is also a northeast canton of Switzerland?

Context paragraphs:
Horn, Switzerland: Horn is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.  Horn is an exclave of Thurgau, enclaved in the canton of St. Gallen.

Arbon: Arbon is a historic and statistic town and a municipality and district capital of the district of Arbon in the canton of Thurgau in Switzerland.

Arbon District: Arbon District is one of the five districts of the canton of Thurgau in Switzerland.  It has a population of (as of 31 December 2016 ).  Its capital is the town of Arbon.

Romanshorn: Romanshorn is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.

Hefenhofen: Hefenhofen is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.

Sommeri: Sommeri is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.

Thurgau: The Canton of Thurgau (German:    , anglicized as Thurgovia) is a northeast canton of Switzerland.

Salmsach: Salmsach is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.

Kesswil: Kesswil is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.

Arbon Castle: Arbon Castle is a former castle and now the "Historisches Museum Arbon" (Arbon History Museum) located in the municipality of Arbon of the Canton of Thurgau in Switzerland.  It is a Swiss heritage site of national significance.

Supporting paragraphs: Horn, Switzerland Thurgau
Answer: Thurgau