The financial crisis seemed like it wouldn't end, so it's pretty hard to believe that the bull market that started back in March of 2009 has already been going on for longer than the ugly bear market that preceded it (10/07-03/09).
Below we highlight the lengths of every bull (green) and bear (red) market for the S&P 500 going back to 1928. The dates represent the start of each bull and bear. As shown, the average bull market (915 days) has historically lasted about three times as long as the average bear market (310 days).
Prior to 1940, we saw a number of short market cycles, but since then they've lasted much longer. In fact, since 1940, the average bull market has lasted more than 1,600 days, which is about 2.5 times as long as the one we're currently in.