Complex sentence: Cedar was the most sought after wood for ties, since it is known for being extremely resistant to rot, however, as electric power came into more common use in the early 1900s, it was substituted with other species such as Tamarack.
Split into simpler sentences: Cedar was the most sought after wood for ties, since it is known for being extremely resistant to rot. However, as electric power came into more common use in the early 1900s, it was substituted with other species such as Tamarack.