A 3 page report (last updated in 2007) from the Congressional Research Service that includes:
- Historical Background About DST in the USA
- Changing an Area’s Time Zone
- Moving an Area On or Off DST
Not only an excellent place to check time the current time for thousands of locations around the world but they also offer this page with info about when each location begins and ends DST/BST.
See Also: Daylight Saving Time (via NASA)