[4][5] The older main road that connects the cities of Skien, Larvik, and Oslo passes through Siljan.

The parish of Slemdal (later renamed Siljan) was established as a municipality on 1 January 1838 (see formannskapsdistrikt law).

The official blazon is "Vert, three saw blades argent palewise in fess" (Norwegian: I grønt tre opprette sølv sagblad).

This means the arms have a green field (background) and the charge is a set of three saw blades standing vertically in a horizontal row.

The charge has a tincture of argent which means it is commonly colored white, but if it is made out of metal, then silver is used.

The green color in the field and the saw blade design symbolize the importance of the timber industry in Siljan.

The tables below show the current and historical composition of the council by political party.