Here's a colorized post card of Ada from the first decade of 1900. The post card identifies its location as South Main Street by moonlight. 

It is possible that the two buildings on the right are part of the Ohio Northern University campus?

Tom Lehman of Ada responds: The old photo of Ada this week is the corner of South Main and University. That is the Brown Building on the corner. In the background behind it you can see the front of the Duke Building which is still standing. They tore down the Brown Building in the 1970s, I believe.

A couple things to notice:
A street light hangs across the street.
The street does not yet appear to be bricked.
The tree lawn is wider than today.

The next photo shows the flip side of the post card, mailed to a Miss Lelia Legler of Defiance.

The post mark is Aug. 9, appearing to be 1908. 

It reads: "Was up to see your mother last night. Every thing is awfully dead and everyone one out of town. Went to church this morning."

Lovingly,
B.M.

It reads like a Twitter message of today.