I'm an undergraduate student about to apply for a Ph.D program this year. I am interested in knowing whether seeking co-advising from a related, but different department (in my case I'm applying for econometrics but thinking about looking for co-advising from the statistics department) is seen as a thing to be encouraged in graduate schools in the U.S., or is it considered a violation of the division of departments?
Also, would it make sense if I mention in my personal statement that one of the consideration of my applying for this school's economics department is that it also has a very good statistics department, from which I can potentially seek co-advising? Would the graduate admission committee be happy to see this kind of statements?