I actually think what could be construed as the "mark" is already upon every American citizen, in the form of their Social Security Number. At one time one's parents had to apply for it, shortly after their child was born, now they're given in hospital along with the rest of the paperwork that accompanies the birth.
So it's a means of cataloging the citizenry, as it were. It's a small matter now of implanting the "chips" we hear about for our pets, etc...
There's already a semblance of the "mark" on driver licenses in various States throughout the country. The magnetic strip that appears on the back, like unto that of a credit card, can be swiped and from that all your personal information is readable. If you put that magnetic strip against a magnet, it deactivates it, so it's unable to be scanned. (I know people that do this so as to protect their privacy) However, in some States,like Florida, if that occurs the police officer can take you into custody immediately, because you have no
legal proof of ID. They may hold you in custody for as long as 3 days, until you can satisfy the court to your identification. And then you are levied a huge fine for that deactivated magnetic strip.
So, I'd say the mark is already here. If anything it's going to get more blatant, when we're told we'll need to get a retinal scan, for our personal security, or a chip implanted, for the same reason. I know military personnel to which that has already occurred. In the event they refused, their discharge papers were waiting in the same room where they chip was to be implanted. Refuse and they had to sign, without opportunity to read the full stack of paperwork, and they were out of the military just like that.
What many people don't know is that, at least in the States, we the people were made "property" of the Government, the moment our birth certificate was issued in the State we were born. So, what comes next is just a matter of inventory of the slave population.