As might be imagined, converting an archive such as we have is an enormous project. Although we have been at work on it for nearly two decades, much remains to be done. On this page we'll list what is online, and what is not (yet). Our goal is for every piece of paper in our holdings to be online. Whew!
First of all, excepting location surveys and Estate files, everything we have is indexed, and those indices are online. If something doesn't show in our search results, either we don't have it, it is mis-indexed (tell us, please), or it is indexed in a way you aren't anticipating. The most certain way of finding a record is geographically searching for it, using the county, tax map and grid format.

What's online so far? All of the SJM packets (the base project files, from 1849 through 1990). All of the SJM fieldbooks. The oversized rolls in the following sections: A1, A2, D1, D2, H1, H2, I1, I2, K1E, K1W, K2E, K2W. Currently we are working on X2, so the early (lower-numbered) X2 rolls are on the site. You will also encounter scattered rolls online in sections not completed yet, because when requests for copies come in, we usually bump that roll to the head of the scanning queue. Also online is the material forwarded us from other surveyors as a consequence of using our archive. (The results of their work.)
Four fifths of the Sutton-Britcher archives are online (envelope 1 through about envelope 2015). They appear as "HCS" entries and live in series 9.
The first 80 or so rolls (of over 2,400) of the E.V. Coonan & Co. archive. Note that Coonan ended up with Thomas Disney's files, who, in turn, had William Shipley's files. Both are here, and ultimately will be online. All are indexed as EVC records: series 10. We were only given rolls of this material; no files, as such, and no fieldbooks, because they are lost.
Most of the oversized Purdum & Jeschke material is online, primarily comprising worksheets and plats. Only around 8 percent of the ordinary file folders (out of the 20 or so 4-drawer cabinets of files) have been scanned, but, as noted above, all are indexed, and many digital records have images in them already. Note also that the P&J setup stored finished plats apart from the actual projects; those plats are nearly all scanned, and are linked on the "Display Record" page to the project files. It should be easy to identify plats of interest. The P&J fieldbooks have not been incorporated yet, but we have them.
The subdivision plats in areas that were annexed by Baltimore City in 1918 are online. (The subdivisions, in other words, that were filed in Baltimore County, but today lie in Baltimore City.) They comprise series 19.
And how about this: the Bouldin family records are here, but, alas, not indexed. The Bouldins were surveyors in Baltimore County (and City) from the late 1700's through about 1910. Their records are in series 17. Additionally, the records of William Smith, George Gouldsmith Presbury and Thomas Gist, all Baltimore County surveyors in the mid-to-late 1700's are here. See series 8. It's a bit difficult finding a particular record though.
Need some railroad val maps? Try Series 13 where we have over 300 of them. All geographically indexed. Ditto for Baltimore City "Original Plats," in Series 18. Come to Papa!
Remember, most of the material outlined above will be included in geographic search results. That is why we recommend that sort of search; it covers most of the bases automatically.
Not included in those geographic indices are the Maps and Atlases produced by the firm in the mid-1800's. But, copies in rough shape, such as are available from the Library of Congress are online and in series 3. We have also digitally restored all our county (and City) maps and offer first-rate prints on museum-quality paper. Contact our office for details.
That's it, so far. We will take requests to bump something to the front of the scanning queue if you can convince us that it is a necessary thing to do. (Take your best shot!). Otherwise, enjoy our stuff.