Poor Grammar

Yesterday, George Will wrote a column on the 70th anniversary of Gone With the Wind. The article contained this paragraph:

Like another Southern woman who wrote a novel about her region, a novel that is still in print nearly half a century later and that became a classic movie (Harper Lee, “To Kill a Mockingbird,” published in 1960), Mitchell never wrote another. In 1949, at age 48, she was killed by a taxi driven by a drunk in Atlanta, which was already on its way to becoming the symbol of the New South.

I know we all make mistakes like this from time to time, but I must admit I can’t make heads or tails of this apparently misplaced modifier. What was on its way to becoming a symbol of the New South?

Margaret Mitchell?
Atlanta?
The taxi?
Or the town drunk?

Feel free to post your thoughts in the comments.