It's generally agreed that, even if the Confederacy somehow became independent, it would still be overshadowed by the United States, and if another war were to happen, the Union would win decisively. The Union had a larger population, more money, more factories, more railroads, and outproduced the Confederacy in agriculture and industrial output.
However, with a POD no earlier than February 4, 1861, have and independent Confederacy and Union be on roughly equal terms with each other by 1961.
Bonus points if:
- The power disparity between the two nations is no greater than that of OTL France and Germany (one can clearly be more powerful, but could plausibly lose a war).
- The Confederacy is made more powerful than it realistically would be, rather than the Union being weakened.
- Both nations are on roughly equal footing by 1900.
- Both nations are at least Great Powers by 1961.