Pennsy track size

I can't remember exactly what I read several yeras back about the Pennsy and the size of track they used. But I recall reading about 150lbs per yard track! Is this correct? If so why so darn big? I recall seeing some older track that was removed and sitting at the maintenance shack of CSX at Effingham, IL that read 140lbs. Was this used on that segment of the old Pennsy? Current track there now is only 132lbs.

When Penn Central laid welded rail on the Main Line between Bryn Mawr and 52nd St. on the local tracks in 1968, 155 pounds per yard Pennsylvania System rail 8 inches high (155PS) was replaced by 140 pounds per yard American Railway Engineering Association rail 7-5/16 inches high (140RE). The "Standard Railroad of the World" did many things in a large way!
In some weights of rail, there was both tall and thin Pennsylvania System rail for passenger trains and short and fat Pennsylvania Railroad rail for freight trains (100PS, 100PR, 85PS, 85PR). Not all of the smaller railroads had their own designs of rail; as you noticed, some used the 132 pounds per yard American Railway Engineering Association (132RE) standard, for instance.