How does Congress correlate to the stock market?

Andrew Roth has the answer:

Mike Ferguson of the University of Cincinnati and Hugh Douglas Witte of the University of Missouri at Columbia, if you had invested $1 in the Dow Jones Industrial Average back in 1897 and held it only on the days when Congress was in session (and vice versa for when they are out of session), here are your returns through the year 2000:

In session: $2
Out session: $216

(via Glenn Reynolds)