Very interesting. Thanks for the answer

Is McPherson wrong in his seminal book Battle Cry of Freedom: The Civil War Era?

On page 108 McPherson states that the negotiated area of the Gadsden Purchase was "55,000 square miles, but northern senators cut out 9,000 of these before enough northern Democrats joined southern senators to approve the treaty in 1854."

But according to Wikipedia and other websites the territory purchased ended ub being 29,670 square miles. So, the figure of 55,000 square miles can't possibly be correct right? Or am I missing something?

I was just surprised to find that this mistake somehow made it to print.