The 1998 Annual Rating List is in the December 1998 issue of Chess Life, starting on page 79. It includes tournaments which finished before October 28, 1998 and were received by November 1, 1998, and players who had played since October 28, 1997. While they do not sort by ratings, they do list the senior masters (2400 and above) first, so you only have a couple of columns to search through instead of a few dozen pages. Old Chess Life issues are currently available online at https://new.uschess.org/chess-life-digital-archives and you can find this issue there.
After skimming the list (using my physical copy of the magazine, which I still have for some reason) it appears that Ilya Smirin had the highest rating at 2728, followed by Vladmir Akopian and Loek Van Wely, both at 2724. Van Wely, however, has his state listed as "FR" indicating that he's French and not US. If you don't count him, then the next player would be Alexander Goldin with a rating of 2715, assuming I didn't miss anyone.