The American Society for Engineering Education (ASEE) publishes reports and handbooks on a variety of topics related to engineering research at the university level. The following graph is a snapshot from the 2010 Profiles of Engineering and Engineering Technology Colleges book, which

Provides many graphs, charts and tables detailing the state of engineering education today. The book also provides a listing for all college enrollments, degrees awarded, faculty and research expenditures at the undergraduate and graduate levels for engineering and undergraduate level for engineering technology.

This graphic shows the most popular engineering doctoral fields in the US, the top five being Mechanical, Electrical/Computer, Electrical, Computer Science and Chemical:

View more ASEE sample data here.