What Math Courses are required for pursuing Economics Phd in US? I have completed the following mathematically inclined courses offered at LSE: 

1) Mathematical Methods (Which includes Linear Algebra and Multivariable Calculus)

2) Elementary Statistical Theory 

3) Principle of Econometrics

I am planning to apply for a Phd program to universities in the United States and I've read on some forums that taking challenging math courses might improve one's chances of getting in highly selective schools. So I was wondering if these courses along with usual Econ courses demonstrate would enough rigour to the admissions committee. I am asking this because I have a chance to specialize in Econometrics and Mathematical Economics in my final year and so if I'm missing some math courses, I might be able to cover them up by choosing this specialisation.
To answer the general question of how to find graduate admissions required or recommended coursework, you can typically visit target program admissions pages. 

If there are official requirements, they will be listed in the prospective applicants section, providing you course types and expected credits/periods of knowledge. If they are recommendations, this gives you a guideline for what you should aim to complete.

For example, UMD asks for:


  In general, our admitted students have GPA's well above a "B" average, particularly in economics and mathematics; very high GRE's (particularly quantitative); math preparation that includes at a minimum three semesters of calculus, a semester of linear algebra, and a semester of differential equations;


I would assume that alternative similar classes, or classes above this level, are also accepted (verify with admissions department, as always).

If this list is not available online or you need help, calling the admissions department is a great way to get info as well. You can provide your list of current and potential mathematics courses and see if you're missing anything.