Page "Economy of Liechtenstein" Paragraph 1

Since the signing of the Customs Treaty in 1916, Liechtenstein and Switzerland have represented one mutual economic area.

Therefore, the borders between those states are open.

The country also uses the Swiss franc as its national currency, and Swiss customs officers secure its border with Austria.

Currently there are 21 Swiss border guards stationed in Liechtenstein and 20 Austria border guards securing its border ( as of 2011 ).