Dates, Centuries and Periods

History runs on dates, and dates are easy to slip on. All the dates in this course are AD, counted forward from the traditional year of Jesus's birth; years BC count backward before it. A decade is ten years ("the 1760s" means 1760 to 1769), and a century is one hundred years.

Key idea

The 18th century is the 1700s. To name a century from a year, take the hundreds part and add one: 1776 → 17 + 1 → the 18th century. In strict counting, the 18th century runs from 1701 to 1800.

Why it works

There was no year zero. The first century AD was the years 1 through 100, so the second century began in 101, and so on. By the time the calendar reached the 1700s, people were already in the 18th hundred years. That is why the number of the century is always one ahead of the hundreds digits. Everyday speech uses "the 1700s" for 1700 to 1799, which matches the strict 18th century for every year except the round ones like 1700 and 1800.

Centuries in this course, with strict start and end years.
Years	Spoken as	Century
1401–1500	the 1400s	15th century
1501–1600	the 1500s	16th century
1601–1700	the 1600s	17th century
1701–1800	the 1700s	18th century
1801–1900	the 1800s	19th century

Worked example: Name the century

Jamestown was founded in 1607. Which century is that?

Hundreds part of 1607: 16.
Add one: 16 + 1 = 17.

Answer: The 17th century (the 1600s).

Worked example: Which came first?

Put in order: the Stamp Act (1765), the Pueblo Revolt (1680), the founding of St. Augustine (1565).

Compare the years: 1565 < 1680 < 1765.
Notice they fall in three different centuries: 16th, 17th, 18th.

Answer: St. Augustine (1565), the Pueblo Revolt (1680), the Stamp Act (1765).

Historians also group years into periods that begin and end at turning points. The AP U.S. History course uses nine. This course covers the first three in this half: Period 1 (1491 to 1607), Period 2 (1607 to 1754) and Period 3 (1754 to 1800). Each start date marks a change: contact between hemispheres, the first lasting English colony, and the war that set Britain and its colonies on the road to revolution.

AP Periods 1 to 3 as colored bands. Each period begins at a turning point.

Common mistake

The 1800s are not the 18th century; they are the 19th. The quick check: the century number is one more than the first two digits of the year. 1848 → 18 + 1 → 19th century. Also watch round years: the strict 18th century ends with 1800, not 1799.

Dates, Centuries and Periods

Practice

Builds on

Leads to

Sources and further reading