Can someone explain the difference between igjennom and gjennom?

Both mean “through”, what’s the difference? I see them being used but there is no apparent reasoning on which to use.

I don’t know of any difference. I only use “igjennom”.

Gjennom is a preposition, while igjennom is an adverb.

“Han måtte kjøre gjennom to fylker for å komme til sin største kunde.”
“Hun var meget fornøyd da hun fikk forslaget om høyere nysalgsprovisjon igjennom i ledelsen.”

It’s a dialect thing I think. I wouldn’t have a problem using “igjennom” in either case. Wiktionary says they’re synonyms.

So would I be safe in simply using “gjennom” always?

I’d use igjennom. I really don’t see any clear difference between those two.

Fair enough. I noticed that I tend to see “gjennom” more in news articles and Wikipedia. “Igjennom” more in just regular writing.

Yeah I find myself using both, not really caring if it’s correct or not.