Confirmed with a search on the New York Times website:
Eclipse of the Sun on July 20 To Pass Over North America; Expeditions From Abroad Join U.S. and Canadian Observers for Studies Along Path From Maine to Aleutians Jets in Pursuit Expeditions on Way Einstein Experiment
By WALTER SULLIVAN
June 30, 1963, Sunday
Page 48, 1544 words
The total eclipse of the sun on July 20, two weeks from next Saturday, is to be the occasion for a sicentific experiment carried out on a scale as grand as the eclipse itself.
(Beyond this point I had to pay $3.95 fo the full article or be a subscriber to the paper. I'm not going to pay for the article when I can probably look up the whole page with the article on microfilm at the library and print it.)
I was 11 then. This was a major deal to me. I was visiting my Aunt Minnie in Oregon on Saturday, July 20, 1963, standing outside in the afternoon trying to use a makeshift device to project the eclipse onto paper or the ground or something so I could view it safely. I didn't have much success so I stole a few quick glances skyward to see if I could see the Moon's bite out of the Sun. Sort of, but it was a little too bright. The Moon covered only about 43% or 34% of the Sun, as I recall. (Short of reading the full article, I have to guess on the coverage in Oregon. I know the eclipse wasn't total in my part of the country.)
The July 20 date has stuck all these years in large part, I believe, because exactly six years later, at 1:17 p.m., Pacific Daylight Time, on Sunday, July 20, 1969, the first humans landed on the Moon, and approximately six hours and 40 minutes later they took the first steps on the lunar surface.