Why does the U.S have an open border with Canada and not with Mexico

Why do we have an open border with Canada but not with Mexico? Why do we have open borders for commerce but not for people? View the following videos before you respond.

Whats the status of Trumps U.S.-Mexico border wall?

https://www.pbs.org/newshour/politics/whats-the-status-of-trumps-u-s-mexico-border-wall

The Wall: A 2,000-mile border journey  https://www.youtube.com/watch?v=RTQDwSVMdNg

60 Minutes on the border https://www.youtube.com/watch?v=oOzvR4SIwGA

Trump’s proposed border wall dividing Texans https://www.youtube.com/watch?v=SaOrAFcOrcY