With good roads and newer cars, Argentina seems like an ideal country to hitchhike in.
While it’s not always easy to flag someone down, locals are becoming more accustomed to seeing grungy gringos on the side of the roads with their thumbs sticking out. 
Argentina also has a Hitchhiking Club, created in 2002, whose website (www.autostopargentina.com.ar) might be worth checking out if you are planning to hitch your way around the country.
Travelers should always keep in mind that hitchhiking is inherently dangerous and must be done with caution and care.