Capitalized:
* When "region" is part of a formal geographic name:
* Southeastern Region (e.g., of a company, organization, or country)
* Southeastern United States
Not capitalized:
* When "region" is used generically:
* The southeastern region of the country experienced heavy rainfall.
* The company's headquarters are located in the southeastern region.
In general, it's best to follow these rules:
* Capitalize proper nouns: Geographic names (like Southeastern United States) are proper nouns and should be capitalized.
* Don't capitalize common nouns: "Region" is a common noun and is not capitalized unless it's part of a formal geographic name.
If you're unsure, it's always safe to err on the side of not capitalizing "region."