Anyplace on an interstate with 3 or more normal lanes in 1 direction it is illegal to use rthe left lane if pulling a trailer or over what I thought was 12000 lbs gross but could be 10000lbs.
I commute to Portland and back for work and see a lot of people doing it,but also see people getting tickets for it.
There are actually quite a few signs posted with the warnings but I think most people just dont notice them.
This subject was talked about several months ago.Unfortunately you must have missed it,or it might have saved a ticket.
Everybody else appreciates the heads up though I bet.