…I arrived on Saturday; he arrived on Sunday.
…He resigned in 2010; she resigned in 2011.
…The first train leaves at 5:00 A.M.; the last train leaves at 10:00 P.M.
The Rule: When two sentences have NO conjunction between them and have parallel grammatical construction, use a semicolon between them.
This question always arises: Could I use a period? My answer is always why would you
pass up the opportunity to use a semicolon? This is one of the absolute semicolon rules.
Use a semicolon here! It belongs here! This is your chance! Be sophisticated!