My university’s department of public safety sent a notice warning about an apparent recent crime spree by a group of teenagers, and in it they state “[a]lways be aware of your surroundings, travel in groups and avoid traveling thru parks after dark”. This was not a short, quick warning, but rather a full document. I had only noticed the spelling ‘thru’ used where space conservation and brevity are important, such as on signs. Has this spelling variation become more common recently?
No reputable author would use that spelling of through…
I don’t see any spike in usage up to 2008: Google Ngram Viewer: through,thru
I also, personally, do not see any increased usage of the word. “Thru” is jarring enough that I’d notice it when reading, and I haven’t been noticing it much.
I’m not aware of it being accepted in that type of formal usage. I don’t mind the word, but it looks jarring outside of a sign or perhaps the phrase “drive-thru.”
I wouldn’t put much stock in this being an “official document.” I’m guessing if your university’s communications department saw it, they wouldn’t be pleased.
This is likely one person’s failure. I doubt if the university style guide would call for the use of “THRU” anywhere but on a sign where limited space is a concern.
I thought it had a nearly-formal usage in phrases like “May thru August”.
In British English, there used to be thro’ (which was still pronounced through), but it’s not in very common usage now.
I do it all the time!
You are correct! 
It’s only really an official document if somewhere it contains a paradox page (a page that is blank except for the sentence “This page intentionally left blank”).
As to the OP, the only comment I have on thru is that whenever I watch the Star Trek episode where Scott is giving Kirk and Spock directions to Gary Seven’s office and keeps saying things like “Proceed five metres, two four seven degrees true,” his dialect always makes me think he’s saying “thru.”
Although it’s been dated back to 1839, “thru” has always been considered, at best, an informal alternative. (Remember that in English grammar circles, “informal” is one step above “illiterate.”)
The Chicago Tribune for years tried to push it as one of their simplified spellings, but even they eventually gave up.
So it sounds like we’re not at the point where thru = through lite
I luv that spelling.
60s Hippy here.
Acceptable in a COBOL program.
Lazy in English.
I’m not usually a fan of this sort of bastardization of a word, but I support this one.
The ‘ough’ ending is such a pain to parse and this adds clairty. I find myself using it more and more, but for some reason I usually limit it to ‘directions’ (i.e. go thru the forest) rather than other uses (i.e. "I’m through with licorice!). I have no rational reason for this.
You must really hate this painting.
Thru is always wrong except in drive-thru
Write some angry letters and get it fixed
“Thru” is better in so many ways that it’s just superior. And it is now mostly listed simply as a 'varient" which makes it mostly legit.
Why the fight to stop AmEng from progressing and improving? Why must English stagnate?
I agri. Wy do we haf to constrain English to stagnation wen der are so many ways to improve the language with superior spellings?
In all seriousness, spelling is a marker of literacy. When I see a writer using a non-orthodox spelling in non-informal writing, I (fair or not) assume certain things about their level of education/socioeconomic background.
Spelling bees are for idiot savants.
agri = no, “agree” ends in a EE sound
Wy=sure
haf= sure
wen= OK
der = I say "f’ not “d”, do you pronounce “there” = “der”?
And sure you do, but altho we can’t all spell any word any which way, it would be useful to allow English to evolve and change some of the worst spellings to better ones.
Is “varient” just a variant of “variant”?
If we can write donut and hiccup, we can write thru.