A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness.

Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

The path of totality started south of Japan, went across the Pacific Ocean, passing northern part of Kitadaitō, Okinawa and the whole Tori-shima in Izu Islands on June 9 (Sunday), and then acrossed the contiguous United States and British Bahamas (today's Bahamas) on June 8 (Saturday).

The path of the eclipse clipped Washington state, and then moved across the whole of Oregon through the rest of the country, exiting over Florida.

Naval Observatory (USNO) obtained a special grant of $3,500 from Congress for a team to observe the eclipse in Baker City, Oregon.

The team had been making preparations since the year before, and John C. Hammond led the first members to Baker City on April 11.

The team included Samuel Alfred Mitchell as its expert on eclipses, and Howard Russell Butler, an artist and physicist.

In a time before reliable colour photography, Butler's role was to paint the eclipse at totality after observing it for 112.1 seconds.

The cloud cover during totality obscured observations of stars,[8] though, preventing this test of the validity of general relativity from being completed until the solar eclipse of May 29, 1919.