I can't comment on the US, but in Canada there are a number of "lecturer" positions, even at research universities. Lecturers only teach; they don't do any research, and it is not necessary to get a PhD to be a lecturer (though I'm sure it doesn't hurt, and some positions do request a PhD). It seems that these positions are becoming more common, especially because the current Canadian government likes to cut costs, so funding is harder to come by. I would suggest searching for these types of positions, and hopefully that will give you an idea of what is out there, how many positions are available, and how many require PhDs.
Here's one example at my university that does require a PhD (in Psychology, not math, sorry).
EDIT: Having said all that, I don't think it's worth continuing your PhD if you're not enjoying it. If you don't like what you're doing, it's going to be very difficult to put the time and energy into completing your thesis. If the area of research is a problem (you're not interested in your research project, or you simply feel stuck), perhaps you can ask your supervisor for a different project, or switch supervisors, or even switch to another department, program, or university.