I've successfully avoided the US for the last few years, but it used to be the rule that you had to clear immigration at your first point of entry* and emigration at your last. Is this no longer the case?
It is correct that you clear immigration at first point of entry, but there is no formal emigration when you leave, this has been the case for the 20 years or so i have been regularly transiting the States. On checking in the agent checks your docs are ok i.e passport, at the boarding gate of your international flight the agent collects the I94 stub or visa waiver stub, you do not see an immigration official. When you check in they often stamp "docs ok" on your final boarding card so that agent knows they have been checked, if not the boarding agent may do a passport check at that time, its very easy and hassle free.