If you have made it this far, you must have the infection...that genealogy infection that unites all us crazy tree climbing folks. Hopefully you will survive, so let's keep going.
Public records are available at three levels. You have already made your trip to your local courthouse, and identified the county clerk's office. Here are the local documents so important to include in your families' history. Make a couple of trips to orient you to the resources available.
The second level is the state or territorial records. In the U.S.A., each state has a capitol which is the center of the state's history. There is usually a State Archives which is specially interested in preserving the state's history and records. These archives begin with the date of admission of the state to the Union. Once you have identified which state your family comes, this would be your next attention getter if you have made the rounds at your local level. They will house many records that have no genealogical value and yet others will contain considerable family history. There is usually a State Historical Society, the State Library, or the State Historical Commission.
The third level is the national. Federal records are kept in the National Archives, Washington, D.C. There are census records, land records, ships' passenger lists, naturalization records, military service and pension records, and bounty land records. The National Archives was founded in 1934 and holds records from 1775. Genealogical records comprise but one per cent of all the records stored in the Archives.
So there you have the next travel itenterery. When your tree climbing takes you further back in history, the second and third levels may be your best resource.