"The longest knitted scarf is 3,463.73 m (11,363 ft 11 in; 2.15 miles) long and was completed after 23 years of knitting by Helge Johansen (Norway), in Oslo, Norway, on 10 November 2006."
23 years!!! I gotta hand it to Helge. I am impressed - and not a little daunted.
Also discouraging is that I have to start over - there are very few requirements for this record, but they do specify the size of the needle (4mm) - I was using 5 - and the number of stitches per row (66!) - I was using 33. Oddly, 66 stitches on a 4mm needles gave Helga a width of 7 inches - whereas I get 13. Not only will this scarf be ridiculously long, it is also unwearably wide. (I was hitting 7 inches width with my 33 stitches.)

I've started world longest scarf, take two. Annoying, each row takes take twice as long as it did with the previous model. Also - a lot of yarn I have already bought at Value Village is too bulky for this size of needles. Sigh.
I was keeping a log book of my knitting - but they don't seem to require anything like that. I don't even have to knit this continuously since they specify how lengths are to be sewn together. At least that solves the problem of portability - based on previous calculations, this 2+ mile scarf could weigh over 200 kgs!
Anyway you look at, this project just gets crazier as I go. In 23 years I will be 56 years old - either vaguely remembering that I once had a foolish ambition to knit the world's longest scarf, or perhaps measuring out my annual length and adding it up to see if I have yet beat Helge's record - this is of course assuming that in the meantime some other knitting maniac hasn't wasted her record - Guinness encourages me to check back in.
So I will be posting regular updates, charting my slow but hopefully steady process from a scarf that is now only a few inches over 2 feet to what will eventually be several feet over 2 miles.