What does the Central Pacific have in common with the song "America the Beautiful," both historically and in wordplay?

Answer:

Historically, the Central Pacific, along with the Union Pacific, built the first transcontinental railroad in the United State - spanning the country from ocean to ocean. 

In wordplay, Central Pacific goes from C to C, while "America the Beautiful" goes "from sea to (shining) sea."

Credit: Idea - Washington Post Crossword
Matt Gaffney
FROM C TO SHINING C