UC Davis, Virginia Tech, University of Washington or Boston University for Mechanical Engg.?

Do you have direct admission to ME at UCD and UW? If not, see
http://mae.ucdavis.edu/changing-majors/
https://www.engr.washington.edu/current/admissions/admitstats

For VT, if you are admitted into the engineering division, see
http://www.enge.vt.edu/undergraduate-changing-majors.html