I've always wondered why the Tappan Zee Bridge is where it is and this week one of my favorite podcasts covered this question. Planet Money is a terrific podcast and when you hear why the bridge was put where it is you may scream or say - oh ok whatever.Planet Money Podcast
Thomas Dewey who was the governor at the time, in what seems to be a slightly ego-based maneuver, places the Tappan Zee Bridge at one of the widest parts of the Hudson River in order to maintain control of the TOLLS of the NYS Thruway and not give up the money to the Port Authority. It turns out that the Port Authority of NY/NJ have jurisdiction of these projects in a 25 mile radius from the Statue of Liberty. So the Tappan Zee is about half a mile north of their control. The bridge is about 3.2 miles when it could have been about 1.1 mile like the George Washington just a bit further south (perhaps near Dobbs Ferry).
Thus Dewey retains control and his super highway which is known to most as the NYS Thruway - is actually the Thomas E Dewey Thurway. Seems things haven't changed much in 55 years with money and politics.