REMOVE

1. hats
2. buildings (structures)
3. garages
4. sky
5. wheels (components)

WHAT

1. automobiles (1)
2. banks (landforms) (1)
3. black-and-white film (1)
4. boys (1)
5. branches (plant component … (1)
6. brick (clay product) (1)
7. bushes (1)
8. children (1)
9. coats (garments) (1)
10. exterior views (1)
11. fields (land) (1)
12. forests (plant communitie … (1)
13. freight cars (1)
14. hills (1)
15. men (male humans) (1)
16. pipes (smoking equipment) (1)
17. plants (1)
18. railroads (1)
19. rails (transit system ele … (1)
20. roads (1)
21. rubbish (1)
22. signs (declatory or adver … (1)
23. soil (1)
24. trains (vehicle groupings … (1)
25. trees (1)
26. utility poles (1)
27. Visual Works (hierarchy n … (1)
28. windows (1)
29. workers (1)
30. wrecks (sites) (1)

WHERE

1. New Windsor, Maryland (1)

WHO

1. Campbell, Sandra L. Still (1)
2. Clyfford Still; Still, Cl … (1)
3. Sandra L. Still Campbell; … (1)
4. Still, Clyfford (1)

More 

WHEN

1. 1969 (1)