Not just differ state by state but also by city. Cars in San Francisco downtown will block there right side so that other car cannot pass them in the parking space area. If they do that to each other, then it's no surprise they do it bicycle. Cops just let it goes, but if that happen in the smaller city around here, they will pull the vehicle over. Unfortunately, they sometime will do the same to cyclist who filter wildly through traffic in the smaller city but it's ok to that in the much more crowded city. It's a jungle out there! If you have to filter, then do it safely and wisely.