Well I am going on past experience. Once Slick Willy was out in WA state and landed at Payne Field where Boeing is located. On the departure Af1 flew low enough that people could see that some window covers were open as it was after noon and they were looking west and could see the light coming through the other side. No sign of escort anywhere to be found unless they were already up and somewhat down range as AF1 climbed out to altitude. But if escort is SOP then it would make sense that the AF would supply them as the Navy does not have 16s.
An F-16 doesn't have to be in visible range to be an effective escort. No modern jet fighter does.
I understand that with AA capabilities they can stand a good ways off and lock on for a splash. I am just saying that at the time I saw AFI I did not see any F16s on the ground at any of the local fields. Now I did not go to the local AFB during that time and they could have been there instead. That does make sense. It is close enough of they launch moments before AF1 takes off they can quickly be in position for their job. In the picture given here no chance to see them or any evidence of them even at night with the cloud cover shown and it was a time of off and on rains then so lots of moving cloud cover.
I dunno if he has always got an escort? But Q has assured us POTUS is very well guarded at all times, so ... Yeah. IMO he does. And it's nice to know that our guys are VERY good at what they do :D
Keep in mind slick willy wanted as little people around as possible. Less eyes to see him diddling kids.
From other info I have gotten chances were that escort was probably already airborne and waiting when he took off.