When did the GOP become known as the GOP? They must have been too young at one point to be known as the GOP, and then there was some break-even point where GOP was a household name. When did that occur?
Considering that the roots of the Democratic Party seem to go back much further. I too have wondered how the Republicans have managed to become known as the Grand Old Party. What is so old (or, come to that, grand) about them?
According to wiki, citing the OED:
Admittedly “Grand Old” being applied to a party which was then around twenty years old seems a bit presumptuous, but it doesn’t surprise me. Since the party name was intended to be evocative of Thomas Jefferson’s original intentions, perhaps the reference was intended to underline this.
I would guess that the Chicago Tribune was using a label which had been applied at times to both the Southern Democrats and the Republicans, as per the OED 1876 cite, helping to cement modern usage.
One might also note that they were enthusing about the election of Benjamin Harrison, and that Grover Cleveland would be back in 1892.
My personal theory is that it is a reference to the Grand Army of the Republic. The GAR was very active in politics in the post war era and a reliable ally of the Repulbican party. The Democrat party was very southern at that time and was seen as the party of the rebellion. Grover Cleveland took on the GAR by taking a harder line on fraudulent pension claims by union veterans.