I second the notion

I agree with you.  Reflective colors would reduce absorption of the sun's energy, and white paint was very common too.

White is it.

We have a lot of refrigerated and freezer warehouses in Oxnard, CA, where I work.  The great majority are white or off-white.  Some have colored accent stripes (complements of the city Planning Dept).  The Union Ice Co. that used to be in town, servicing the PFE icing platforms, was also a white building.

The reason is white and off-white, and very, very light pastels, reflect the most light by far.  Even medium light colors like tan, beige, adobe, etc. absorb a significant amount of solar radiation.  Metallic coatings such as aluminum and silver actually absorb a lot of radiation.  At the elemental level they appear dark.  If you use a magnifier or micorscope, they many times appear block.   Here's a test:  On a sunny, hot day, put your hand on a white car body, then a black car body.  OK, you know the result.  But now, put your hand on a shiny metallic surface like a chrome bumper.  Caution:  the burn will be greater than the black car surface.

So, white is it.

 Edit:  to include roof comment.

50's roofs, and some 60's, got aluminum paint, with the thinking that it would reflect.  But as the roof failures accumilated, they tended to switch to white cap sheets (they kind of look salt and peppery - white with black specks).  I did some construction engineering consulting work for the Navy in the 80's, and one of their problem children was roof failures.  Guess what they were still using for roof coatings?

Raw concrete

The ones in the Salem area tend towards white or cream if they painted it, raw concrete if they didn't bother.

Americold in Salem is a very large cold storage outfit - this is what they look like from the top: 

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=americold,+salem,+oregon&sll=37.0625,-95.677068&sspn=39.86519,55.634766&ie=UTF8&ll=44.977709,-123.000537&spn=0.004356,0.006791&t=h&z=17

Street View (I hope):

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=americold,+salem,+oregon&sll=37.0625,-95.677068&sspn=39.86519,55.634766&ie=UTF8&ll=44.976328,-122.999829&spn=0,359.993209&t=h&z=17&layer=c&cbll=44.976262,-122.99989&panoid=JBNfd4J5rrg5-jLsRY635g&cbp=12,321.6176411987516,,0,9.265402843601896

Obviously a foggy morning, but you can still see what I mean by raw concrete.