According to Miles & Posner (2008) "Which States Enter into Treaties, and Why?"
The average for North America is more than ten times that of Africa. The North American average is driven by the United States, which is party to 7,181 bilateral treaties. The next most active nation, France, is party to 3,707 bilateral treaties. The third most active, Spain, is party to 2,527 bilateral treaties, and China is the fourth most active with 2,490 bilateral treaties. North America has nearly five times the average number of bilateral treaties with states as the second-ranked continent (Europe). The average state has entered 463 bilateral treaties.
Is there a qualitative explanation why France has substantially more bilateral treaties than other EU countries? (The paper doesn't offer it.) I can think of former colonies, Canada etc., but then Spain or the UK also had colonies etc. So why does France have so many bilateral treaties?