PhD in Mathematics is the big question. Why do you need a higher level of mathematics education? Because you need to advance from the undergraduate level to the graduate level to teach in an advanced school level. A master's or doctorate degree in mathematics is usually required for teaching in a high-level school. And most professors want students with doctoral degrees. A PhD or master's degree will allow you to be more specialized in a certain field, but you can still teach in high school and in many community colleges. You can also specialize in another area, like computer science, to take advantage of a broader range of students.
The curriculum that you need depends on the area in which you hope to teach, so check the requirements for that area when you apply for admission to a college. In most cases you'll need a bachelor's degree before you apply. However, it doesn't always have to be a four-year program. Many community colleges offer a bachelor's degree that is equivalent to an associate's degree. The bachelor's degree often has less of a focus on mathematics and more of a focus on business or other non-mathematical subjects.
Masters and doctoral degrees are offered by a number of universities and colleges. The only way to determine what programs are available at the school you're applying to is to visit the site of the accrediting agency that oversees the programs. Most community colleges offer these kinds of programs. It may be harder to find a program at a larger university, but it is possible to get a master's degree, or even a doctoral degree through some schools.
If you're going to receive a doctoral degree in mathematics, there are a few steps that you should follow. First, you'll need to submit a proposal. Then you'll need to write a dissertation. Although you don't have to complete a dissertation in order to obtain a Ph.D., it is highly recommended that you do, as the dissertation is what makes the distinction between a good student and a great student.
Once you get your doctorate degree, you can continue your education by attending a graduate program in mathematics or getting a masters in mathematics. and obtaining a Doctor of Education in Education Administration. You'll still be able to teach at a college or university level, if you like, but now you'll have two advanced degrees to show for your hard work.
Getting a PhD in . . . . . . mathematics isn't quite as difficult as it might seem. If you look around you'll find plenty of programs.