This picture was made in 1915, with a large-format camera (probably a plate camera). Estimating depth-of-field is slightly hard as he quite likely used camera movements to shift plane of focus so it lines up with the line of the building. It's also slightly hard to asses the shutter speed as the image has been printed fairly softly (Strand was in the process of moving away from pictorialism to modernism, and this photograph is one of the examples of that move). However there's nothing significantly out of focus in the image, so the answer is 'enough DoF, combined with movements, to keep everything in focus'.
It's possible to make some kind of numerical estimation: if you guess at a film (plate) speed of ISO 25, which is probably reasonable (although it's hard to get information about very old emulsion sensitivities) then you can see there is some motion-blur in people's feet, so may be an exposure of 1/8s or so. It's sunny, so using sunny-16 - 1 (25th at f/8) I get perhaps f/22 or f/32. Those would be reasonable apertures for a LF camera (all the shutters I have go down to f/45, and Group f/64 was called that for a reason).