Complex sentence: The United States Post Office Department established a post office at Valley on May 19,1928, and it was disestablished on June 15,1937 with its mail routed through the post office in Romney.
Split into simpler sentences: The United States Post Office Department established a post office at Valley on May 19,1928, and it remained in operation there until its disestablishment on June 15,1937. Following the closure of Valley's post office, its mail was routed through the post office in Romney.