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.

[1] The path of totality was visible from parts of modern-day eastern Russia, Alaska, western Canada, Washington, Idaho, Montana, Wyoming, Colorado, New Mexico, Kansas, Oklahoma, Texas, Louisiana, Cuba, Haiti, and the Dominican Republic.

Newspapers in the United States reported of large migrations from the Midwest towards the path of totality to view the eclipse.

[2][3] The 1878 eclipse was a turning point in modern astronomy, because it was the first time that many of the world's leading astronomers had the opportunity to make their observations from the higher altitudes provided by the Rocky Mountains.

After the 1878 eclipse, astronomers began to build observatories at locations well above sea level, including on the sides and summits of mountains, a scientific trend which extended throughout the twentieth century and into the twenty-first.

Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee).