Today I was driving to a doctor's appointment that I had in Idaho Falls. I was leaving from Saint Anthony. As I was going through construction in Saint Anthony, I was in the right lane coming up on a semi. In the left lane was a 2003 Lincoln Aviator. He was passing me. As I was waiting for him to pass me so that I could pass the semi, he slowed down and rode by my side. I went to pass him so I could pass the semi, and he sped up. Once I got back over in the right lane, the vehicle started following my car, and the driver was recording while driving. There was another passenger in the passenger seat. The man followed me concerningly close and did not put his phone down. He began speeding up to pass me while recording. He would then pull back into the lane in front of me and slow down to 60/50 mph. I needed to get in the left lane due to vehicles approaching the highway from the on-ramp, and he would then speed up and get in front of me. The driver would sometimes speed up and get a couple of cars ahead of me but would keep adjusting his rear-view mirror, which I assume was to keep an eye on where I was. This went on until I got to Ucon. I pulled off at an exit to allow the driver to get away from me while he was still ahead of me. The recording of me and my vehicle went on clear from Saint Anthony to the Ucon exit. I had not done anything to make sense of why he would be harassing me, recording me, or following me. It concerns me for my safety due to the fact it went on that long, and the fact that he had his phone in his hand in front of his face while driving.