The US Education system is very flexible. There are many types of degree programs offered at every level. Choices are enormous and one is not restricted to a particular field of study. If you have an excellent academic record in any field, you can aply to any field that you are passionate about. For example, if you have a Bachelors degree in Electrical Engineering, the M.S. in Electrical Engineering at UC Berkeley could be a great choice for your higher education. But let us see what all degree programs you could apply for:
You can directly apply for a Ph.D. in Electrical Engineering at Princeton
or an MBA at Kellogg.
You can apply for a PhD in Business at Wharton
or PhD in Mathematics at Duke
if that interests you.
You can apply for a dual degree in Master of Computer Science and MBA at UIUC. You can apply to unique, multidisciplinary programs like the MS in Management Science at Stanford or MS in CDO at MIT.
You can even apply for a Masters in Public Policy (MPP) at the Harvard Kennedy School or a MS in Environmental Engineering at UT Austin or MS in Computational Biology at CMU
or an MS in Financial Engineering at Berkeley.
There is high degree of flexibility and academic freedom at US Universities. You could enroll for one degree major and change to another, or get additional (dual) degrees. You can take courses in another department, perform interdisciplinary research or get a minor in an unrelated field. You can enroll in Computer Science and your research topic could be related to Bioinformatics.
Awareness and interest are the two most important factors that should determine your choice. Be aware of all the choices and then make an informed decision based on what do you really like. Do not apply for certain programs because someone else did so or because by opting for a particular program you believe you may get funded.