Not in all milk in the US and most milk products, like yoghurt, do not use cows treated with rBGH.
However, it does occur naturally in milk anyway.
In fact the top 3 grocery retailers in the nation, Wal-Mart, Kroger, and Costco do not sell milk that is from cows treated with rBGH. Nor does Safeway, Starbucks, Publix, Kroger and Ralphs.
Which makes me wonder who is buying the stuff anyway.
In 2007 17% of cows in the US were treated. Given the amount of stores that do not carry the products one can only assume the amount has dropped since almost all of those bans came in around 2008.