The Treaty of Tordesillas didn't establish a specific degree of latitude. It established a line of demarcation that ran north-south, approximately 46°37' west of the Greenwich meridian, dividing the newly discovered lands outside of Europe between Portugal and Spain.

This line didn't correspond to a specific degree of latitude, but rather a longitude that would split the world in two, granting Portugal control over lands east of the line and Spain control over those to the west.

The exact location of the line varied as geographical knowledge improved, but it was originally intended to be a vertical line, not a horizontal one.