Complex sentence: The first route across Lake Michigan between St. Joseph and Chicago began as a mail route in 1825, but service was sporadic until 1842 when Samuel and Eber Ward began a permanent service.
Split into simpler sentences: The first route across Lake Michigan from St. Joseph to Chicago began as a mail route in 1825. Sporadic service to and from St. Joseph continued until 1842 when Samuel and Eber Ward began a permanent service.