Whether or not you decide upon a major prior to entering college, consider the following. Knowing these bits of information upfront should put your mind at ease about applying to a college 'undeclared.' Doing so does not sanction you as an indifferent, undedicated, or lackluster candidate; rather, you might be honestly searching. As J.R.R. Tolkien said, "All who wander are not lost." This is particularly applicable to those exploring potential majors.
Now, of course, it's great to have a major well defined before stepping foot on campus; especially if the major is in engineering, pre-medicine, architecture, or the hard sciences. If you don't attack these subjects till late in your sophomore year, you might need five, six or more years to graduate. However, for most students, a bit of introspection, exploration, curiosity, and investigation might be called for in mapping out a major.
You might begin by doing some research, which doesn't necessarily have to be directed. The College Board website: http://www.collegeboard.com/csearch/majors_careers/profiles/ is a good place to start. It contains a profile of majors ranging from agriculture to theological studies, as well as a number of careers. I looked under "economics," which was listed under "social sciences." It gives a sense of the type of courses one might take, and the type of careers an economist might explore. If this site helps you actually unearth a major, you can then turn to the CollegeBoard's Book of Majors with its listing of 900 majors at 3,600 colleges, to find which colleges offer the major. Another good source is Rugg's Recommendations, a stalwart source for matching majors and schools.
If you're unsure of what you're interested in, a good, inexpensive way to start figuring out your interest is with a Holland Interest Survey (which gives you feedback on whether you're realistic, investigative, artistic, social, enterprising, or conventional). Interestingly enough, John Holland worked for the ACT, so this survey is included on the ACT test. When you receive your ACT score, look at the findings on your interest survey; they just might point you in the direction of some promising major.
As I mentioned in a recent column about internships, the more things you try, the more familiar you'll become with a variety of disciplines. Talk to as many professionals in the fields you find interesting, even fields that are marginally interesting. Get to know exactly what their jobs involve. Find out whether what they do now relates, even remotely, to what they studied in college. People find their professions by following a number of paths, many indirect and seemingly unrelated. Knowing their stories, as you undertake your own search, might prove valuable.
If, despite all your best efforts to determine a major, you enter college undeclared, don't lament. College is a great place to discover your interests, if you keep your mind open. Most colleges have general education courses, or a core curriculum, that require you to stretch and explore a range of disciplines. So a survey course in geology, something you might have never contemplated taking, might spark further exploration. A lot of courses you took in high school might prove to be quite a bit different in college. So don't discount potential subjects based on high school encounters. Anything is possible if your mind is ready.
Deciding on a major will not limit your career possibilities. Don't be swayed by this myth. I had a friend who majored in English at Tufts. After she graduated, she went to a gynecologist, whom she disliked to such a degree, that she decided to become one. She went back to Tufts, took all the science courses she had avoided like the plague as an undergraduate, took the MCAT, went through Tufts Medical School, and now is the head of the gynecology department at Massachusetts General Hospital. There are a lot of unusual stories about majors, careers, and life. Don't be afraid to create your own.