Take A Back Seat
Meaning
Take a subordinate or obscure position.
Origin
This phrase has a straightforward and literal derivation. It alludes simply to the back seats, of a coach, a theatre etc., being less prominent than the others. It originated in the USA in the mid-19th century. As we might expect, the earliest uses of the phrase merely refer to people sitting at the back.
The first use that I can find of the figurative use of the phrase, i.e. one where no actual seat is occupied, comes from The Daily Wisconsin Patriot, May 1859:
“The despised foreign born slave – the much hated and often cursed ‘Irish,’ ‘Dutch’ and ‘Norwegians,” must take a back seat in the exercise of all the foregoing announced privileges [voting, jury duty etc.] – no man of foreign birth can vote until two years after he shall have received his full papers.”