When the Poughkeepsie bridge burned in 1974, a vital link in the Alphabet Route (NKP/WLE/PWV/WM/RDG/CNJ/LHR/NYNHH) chain was broken. The Alphabet Route provided routings between the Midwest and New England and the Midwest and East Coast ports that were an alternative to the larger railroads (NYC, PRR, B&O and Erie) that could connect the Midwest with the East. The smaller roads provided a well-coordinated service, with a practice of making these trains among the hottest on their respective railroads.
The loss of the bridge eliminated the Maybrook gateway to New England, and the huge New Haven yard there had no use, as the New Haven route to New England was severed. At one time, the yard hosted trains from the New Haven, Erie, Lehigh & Hudson River, Lehigh & New England, and New York Ontario & Western, all providing traffic that was routed over the Hudson River at Poughkeepsie.
Of course, this spelled doom for the Lehigh & Hudson River. With little on-line traffic other than the zinc mine at Ogdensburg, the struggling L&HR depended on the Maybrook traffic to keep itself afloat. On the other hand, the Penn Central benefitted in two ways. First, there was no more need to maintain the former New Haven west of the bridge, and traffic that had belonged to the competition west of Maybrook had to be routed via an all-PC route. Many people suspected that the fire had deliberately been set by the Penn Central, including L&HR president W. Gifford Moore, who stated it publicly at an ARHS convention in Warwick, NY quite a few years ago.
With no more overhead traffic, the L&HR limped along for two years until its inclusion in Conrail. Conrail quickly relegated the once well-maintained L&HR main line to a weed-infested branch. Twelve years later, the revitalized Susquehanna restored its main west of Butler, and also rehabilitated the newly-acquired L&HR line from the interchange at Sparta Junction to Maybrook. Here, the first through freight to travel over these rails since the Poughkeepsie Bridge fire twelve years earlier rolls through East Chester, New York.