REMOVE

1. railroads
2. mountains
3. trees
4. silver gelatin
5. utility poles

WHAT

1. buildings (structures) (1)
2. exterior views (2)
3. forests (plant communitie … (2)
4. landscapes (representatio … (2)
5. railroad stations (1)
6. roads (1)
7. sky (1)

WHERE

1. Alberta, Canada (1)
2. Lake Louise, Alberta, Can … (1)
3. Pacific Northwest (1)

WHO

1. Clyfford Still; Still, Cl … (2)
2. Still, Clyfford (2)

WHEN

1. 1920 (2)
2. 1945 (2)
3. between circa 1929 and ci … (2)