Detailed Instructions: Given a text, write a compressed version of it in a single sentence.
Q: The difference in labor costs for rural and city carriers has its roots in the development of the two crafts. In another postal system there might be no differences in the compensation of city and rural carriers or it might be much larger.
A:
The difference in labor costs for rural and city carriers has its roots in the 2 crafts. In another postal system there might be no differences in the compensation between the 2.