Here is MRN's official list of stations for NASCAR in North and South Carolina (Not all races air on all stations):
WQDK-FM 99.3 Ahoskie NC
WMXF-AM 1400 Asheville NC
WQNS-FM 104.9 Asheville NC
WMMY-FM 106.1 Boone NC
WBAG-AM 1150 Burlington NC
WFNZ-AM 610 Charlotte NC
WEGO-AM 1410 Concord NC
WGAI-AM 560 Elizabeth City NC
WKML-FM 95.7 Fayetteville NC
WAZZ-AM 1490 Fayetteville NC
WNCC-FM 96.7 Franklin NC
WTQR-FM 104.1 Greensboro NC
WHKY-AM 1290 Hickory NC
WAME-AM 550 High Point NC
WCXL-FM 104.1 Kill Devil Hills NC
WCMS-FM 94.5 Kill Devil Hills NC
WLNC-AM 1300 Laurinburg NC
WLXN-AM 1440 Lexington NC
WKXU-FM 102.5 Louisburg NC
WCVP-AM 600 Murphy NC
WCVP-FM 95.9 Murphy NC
WCNG-FM 102.7 Murphy NC
WRHT-FM 96.3 New Bern NC
WRHD-FM 103.7 New Bern NC
WNNC-AM 1230 Newton NC
WQDR-FM 94.7 Raleigh NC
WKRX-FM 96.7 Roxboro NC
WWGP-AM 1050 Sanford NC
WAME-TR 92.9 Statesville NC
WRGC-AM 680 Sylva NC
WKSK-AM 580 W. Jefferson NC
WWQQ-FM 101.3 Wilmington NC
WAAV-AM 980 Wilmington NC
WZLA-FM 92.9 Abbeville SC
WCAM-AM 1590 Camden SC
WTMZ-AM 910 Charleston SC
WQNT-AM 1450 Charleston SC
WJKB-AM 950 Charleston SC
WPCC-AM 1410 Clinton SC
WMFX-FM 102.3 Columbia SC
WZMJ-FM 93.1 Columbia SC
WWRK-AM 1400 Florence SC
WDSC-AM 800 Florence SC
WEGX-FM 92.9 Florence SC
WESC-FM 92.5 Greenville SC
WBZT-FM 96.7 Greenville SC
WRHM-FM 107.1 Rock Hill SC
WVSZ-FM 107.3 Rock Hill SC
WALI-FM 93.7 Walterboro SC
This is PRN's list (Charlotte among the tracks):
http://www.goprn.com/affiliates/stations/sprint_cup_series/
There's a lot fewer stations carrying races compared to 1998, when it seemed like almost every major country station in the Carolinas carried the races:
http://groups.google.com/group/rec.autos.sport.nascar/msg/e467ff9a9371ac7b?hl=en&&q="MRN+Radio"