When you are referring to the era itself, you always capitalize. However, all of these "era names" are also used as adjectives or nouns without capitalization as well. The girl was a colonial because she lived during the Colonial Era of American history.

Should colonies be Capitalised?

Lowercase colonies, not Colonies. Lowercase light infantry, not Light Infantry. ... For state congresses, use lowercase congress. Continental: Capitalize.

Do you capitalize colonial home?

Capitalize colonial when it refers to a specific era in U.S. history or a style associated with that era: ... When you're talking about other countries, capitalize colonial in reference to a specific style but not in generic uses: The design was influenced by British Colonial architecture.