REMOVE

1. boys
2. shadows
3. neckties
4. artists (visual artists)
5. plants
6. sitting
7. barriers

WHAT

1. automobiles (1)
2. black-and-white film (1)
3. buildings (structures) (1)
4. coats (garments) (1)
5. driveways (1)
6. exterior views (1)
7. freight cars (1)
8. hats (1)
9. houses (1)
10. lamps (lighting devices) (1)
11. men (male humans) (1)
12. neighborhoods (1)
13. parking lots (1)
14. purses (ladies' accessori … (1)
15. railroads (1)
16. rails (transit system ele … (1)
17. roads (1)
18. rock (1)
19. rubbish (1)
20. sidewalks (1)
21. signs (declatory or adver … (1)
22. sky (1)
23. soil (1)
24. trains (vehicle groupings … (1)
25. trees (1)
26. trucks (1)
27. utility poles (1)
28. Visual Works (hierarchy n … (1)
29. wheels (components) (1)
30. women (1)
31. workers (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)