They don't need to subdue 64 million they should need to round up, inter, imprison, tag, or shoot many ring leaders and community leaders. I don't think about large sale civil unrest for generations has involved trying to control everyone.
Grab the leaders and agitators and most vocal
Control the power supplies and water supplies
Turn off the phones and interweb
Control the food supplies
Stop the public transport
All covered in depth in the Emergency Powers Act
Imagine the sheeple kick off and the next morning they get up and the phones / web is turned off, the shops are shut, the buses and trains aint running, then if the sheeple keep kicking off they turn off the leccy, gas and water.
Forgot to mention the banks as well, the gummint could just as easily order the banks to close and the cash points turned off, add that to the simple measures above and without having to shoot anyone they should break most uprisings.