Hi,
One of the riddles of astrology is the fact that it it may indeed illustrate the inner structures of time - among others its symmetries. That means the birthtime is a kind of midpoint: e.g. the tenth year is "reflected" in the corresponding charts ten years before the birth.
This works well with Tertiary Progressions and with solar charts.
And it helps a lot when it comes to finding out the "right" chart.
The above chart is the converse solar of the USA for the time July1860-July 1861 - in April 1861 the Civil War began.
The converse solar is based on the chart with the SAG-AC at 7 degrees.
There's no need to point out in detail what is so clear. Another point for the 7 SAG chart, isn't it?

The strange thing: at times the converse charts are even more "accurate" than the "common" ones.

Regards,
LL