Many business's are incorporated  as a corporation or organized as an  LLC under one name, but conduct business under a registered trade name or fictitious name. You might start your search with your state's Secretary of State. If you do not find it you will need to check your state's statutory requirements for registry of a trade name/fictitious name to determine where else to look. If you check Dunn & Bradstreet's website they provide a free search service which may also be helpful..I use it routinely to locate a trade name for collection cases. Remember...trade names and fictitious names have no legal identity for purposes of collection suits. You have to sue the business under its corporate or LLC identity with a reference to its trade name or fictitious name.

                   Example:   XYZ, Inc. dba  ABC Enterprises

In Connecticut trade names are registered with the Town Hall of the town in which the business's principal office is located