Complex sentence: Construction began on July 4,1828, when Charles Carroll of Carrollton did the groundbreaking, and the first section, from Baltimore west to Ellicott's Mills (now known as Ellicott City), opened on May 24,1830.
Split into simpler sentences: Construction began on July 4,1828, when Charles Carroll of Carrollton did the groundbreaking. The first section, from Baltimore west to Ellicott's Mills (now known as Ellicott City), opened on May 24,1830.