Question regarding concrete whistle posts

Does anyone happen to know the approximate date of installation for concrete whistle posts and mile posts on the former Michigan Central? We are looking to give a approximate date of origional installation to a whistle post we recently rescued and relocated to a outdoor RR equipment display in Lapeer, Michigan on the former MC RR Bay City branch.
It goes nicely along with our ex NYC, GTW and DT&I cabooses. Thanks!

They most likley date back to the early 1900's.

SRS125 wrote:They most likley date back to the early 1900's.

Thanks SRS, They do date back to pre-1917 as they show up on the Valuation maps that I have from 1917 on the Bay City Branch.
After doing a little more digging I am leaning towards using 1905 as a possible installation date, the year the line was reworked and new rail was installed. Thanks again for the reply, I realized when I posted this question that I most likely wasn't going to find the exact date, your imput is appreciated.

I have also seen some of thows White Tomb Stone style mile markers made of wood as well these were from the NYO&W.