I recentley moved to Fairbanks AK, and was wondering if Alaska constituted being north of line A. Being that geographically, Alaska is north of line A, but in real world applications, Fairbanks is nowhere near Canada.
Reading http://www.gpo.gov/fdsys/pkg/CFR-2012-title47-vol5/xml/CFR-2012-title47-vol5-sec90-7.xml, I cannot find that any part of Alaska is "north of line A", but some of it may be "east of line C". Line A doesn't start until Aberdeen, Washington, so to be north of that line you would have to be in the northern Continential US or in Canada. Alaska is not geographically north of that line. This is why there's a Line C - to cover the Canadian/US border shared with Alaska.
tl;dr: Line A is not relevant to Alaska. Line C, however, is, but it is does not affect the Amateur Radio Service.
The surest way to get a clear answer about Lines A and C is likely to use the FCC Line A & C Check utility to find out based on your latitude and longitude which side you're on. You can also consult the Line A & C map to get a quick sense of where the lines run. If you are in Alaska east of 143 degrees West longitude, you should perform the more detailed check.
That said, Line C is not mentioned anywhere in the FCC Amateur Radio Rules (47 CFR §97). It appears to apply predominantly to the General Mobile Radio Service (GMRS) and the Private Land Mobile Radio Services (PLMR).