On Saturday morning July 4, 1908, the Thousand Island Special, or Clayton Flyer, as it is known among railroad men, on the Rome, Watertown & Ogdensburg Railroad ( R. W. & O. ) , was heading northbound filled with holiday excursionists. The train was composed of six sleepers, a day coach, a combination baggage and smoker, and an ordinary baggage coach—nine cars in all, drawn by two engines. This was a little more than the average size of this train.

The train left Utica, NY with Engineer Rieber and Fireman Lingerfelder on the leading engine and Engineer O'Brien and Fireman Brunett on the second.

Also on the R. W. & O. Railroad, southbound, was freight train No. 90. There were about 20 or 25 cars in the freight train which were filled with various shipments from the northern country, much of it being dairy produce, groceries and general merchandise. One of the first cars on the train was loaded with cheese. Fireman Palmer was usually at work with the engineer on this freight, but Saturday morning Mr. Michael was taking the run, with Engineer Hughes.

Denley, NY is the next station beyond Boonville, NY and the Black River road there depicts what might be called the middle part of an elongated letter “S” along the Black River Canal. The freight train came into the gradual curve from the upper part of this “S”, and in so doing came into a gentle but decided grade. So in any case it would be difficult to stop a heavy freight train at such a place, even though the track was straight for miles and an approaching train could be seen. The baggage man of the passenger train, stated that he felt the brakes being set even as the collision came.

The collision came at 6:30 am nearly midway between Denley and Boonville, which was about a mile and a half north of Boonville. With an impact, the sound of which was heard at least a mile away, the Thousand Island Special crashed head-on to freight train No. 90 piling engines and cars into a mass of wreckage killing four men outright and injuring 10 or more, two of whom later died in hospital.

In an instant the trains had toppled over towards the canal, and four lives had been forfeited. The dead: Albert Rieber, engineer, Utica; Stephen O'Brien, engineer, Utica; Andrew Wolner, trainman, Utica; Joseph Michael, trainman, Adams; F. W. Brunnet ( died in hospital ), fireman, Watertown; and John O'Brien ( died in hospital ), Glenfield.

In that same instant, other portions of the two trains were being wrecked and thrown from side to side to the sound of splintering wood, the rumble of freight cars striking into each other pilling up and falling over. Inside the cars passengers were thrown about and the injured were jammed against seats and against car windows. The cow catchers on the two engines that met were demolished and the boilers interlocked. The second engine on the passenger train remained on the roadbed, but left the tracks, which were torn up for a distance of several hundred feet. The day coach back of this engine did not leave the track, as did the remains of the combination car and baggage car, the latter of which lay beneath the combination, a total wreck.

As for the freight train, four cars were tumbled about back of the engine which had drawn them. The second of the freight cars piled itself up on top of the first and both rolled over into the marshy land near the track on the side of the canal. Two more, immediately back of them, rolled over into the ditch on the other side.

The wrecking crew from Utica, under Mr. Griffin, was summoned as soon as possible and the train was started shortly after 7 o'clock. The wrecking crew from Watertown was also put at work on the big task of clearing track, and help was also secured from Syracuse. A big party of laborers was kept busy laying a new track as soon as the twisted rails were taken out of the way.

After a thorough investigation in the weeks following the accident, railroad officials declared that the wreck was caused by operator's error in transmitting orders, the result being the worst disaster in the history of the R. W. & O. Railroad since the road was established.