Eras in America

[Verily]

pre-1607: Pre-Colonial
1607-1689: Early Colonial
1689-1763: Late Colonial
1763-1787: Revolutionary War
1787-1803: Federalization
1803-1848: [First] Westward Expansion
1848-1865: Civil War
1865-1876: Reconstruction
1876-1900: Industrialization (also Gilded Age and Second Westward Expansion)
1900-1918: Progressive Era (could maybe combine with Industrialization if desired)
1918-1929: Roaring Twenties
1929-1939: Great Depression (could combine with Roaring Twenties if desired)
1939-1946: Second World War
1946-1991: Cold War (may be divided into the Early Cold War and Late Cold War by 1963 if desired)
1991-2003: Computerization (also International Dominance)
2003-Present (?): No good name since it's not clear whether the period beginning in 2003 has even ended or not. "The Decline" is probably too much in reference to the period preceding it and may not properly characterize the current period when analyzed in the future.

Note on Civil War and Revolutionary War: They include periods before the war started because those periods are essential to understanding the wars themselves. Since the other wars which give their names to eras on this chart were not of domestic origin, the lead-up to them is of much lesser significance in American history and therefore not included with them.

Second World War contains two years before the United States' entrance into the war and one year following its conclusion because the events of the war nonetheless dominated domestic and international affairs despite no American involvement in conflict (and no conflict at all in 1946).