Image Making for a National Audience

Joe Biden and Donald Trump are not yet the official presidential nominees of their parties, so voters have not had the opportunity to watch them go head to head, as in 2020, in a debate or interview setting. But on Thursday, as each visited the U.S.-Mexican border to address the issue of immigration, the two were as close to a face-off as has been seen since the last election — even if they were 300 miles apart.

The result was a picture not…