Usa Flags

What are the three flags that are flown at the border of USA and Canada?

When you cross into Canada from the United States, you always see 3 flags. There is the US flag on the US soil, and a Canadian flag in the Canada side. What is the third flag that is flown at the border?

The blue one in the center is the United Nations flag

HELLA BARS – YOUNG NOBLE AND HUSSEIN FATAL