Some records for Baltimore County families may be still found in the Baltimore City Archives. I know of one case where there are Court papers for one of my ancestors from 1813 or so that divided his land among his children that were found in theBaltimore City archives, while the property and he were located in what was and still is in Baltimore county.
Address and Phone Number for the Baltimore City Archives:
Baltimore City Archives
2165 Druid Park Drive
Baltimore, MD 21211