This is the 3rd tier of apostille system in the USA in accordance with The Hague Apostille Convention.
Public documents at the level of a U.S. state, the District of Columbia and other U.S. jurisdictions (examples listed below) may be legalized with an apostille by designated authorities in each jurisdiction (for acceptance in countries-parties to the Hague Apostille Convention without any further certification) or certified by designated authorities for further chain legalization (sometimes called "Standard Certification") via U.S. State Department and foreign embassy for use in countries that are not parties to the Convention.
Other U.S. Jurisdictions are:
Public Documents (at the level above relevant to the 3rd tier):
The designated authorities exist for every state in the USA (usually, the state Secretary of State's office), District of Columbia (DC Office of the Secretary) and all other jurisdictions with the exception of the Virgin Islands where no authority was designated.
Usually, a client can easily do the above apostille/certification at a state level himself/herself. However, in certain cases when a client needs a speedy service and/or if he/she is out of the country, then we get asked to do notarization, authentication/apostille at the Secretary of State level. Since we are located in DC area, we often take our documents to the Secretary of the District of Columbia. Please see Our Fees that include services at the Office of the Secretary of the District of Columbia.
Furthermore, WDC Apostille & Legalization Services due to presence of its agents in Washington, DC generally steps in to provide the services for either apostille at the U.S. Department of State or the chain legalization - i.e., for authentication at the U.S. State Department and legalization at the foreign embassy/consulate/mission in question.
We hope to hear from you soon!