I want to become a Quantitative Analyst, would majoring in Economics (and/or Mathematics) be the way to go? If not, what is the better route?
If I understand that term in the same way you do, yes, a major in economics and/or math might be appropriate pathways. Other possible pathways might include majors in statistics, data analytics (“big data”), politics or psychology or sociology with additional coursework in quantitative methods, operations research, etc. A lot depends on what type of work setting or applications you have in mind for utilizing your quantitative skills.