Canada does appear to have changed colours with the rates.

1903 Edward VII

1c green printed matter,
2c carmine postcard ,
5c blue letter.

US 1c special postcard Rate:
http://images.andale.com/f2/104/103/..._Scan10081.jpg

2c postcards to Peru + Belgium
http://filateliamk.freeservers.com/1105/53981a.jpg
http://filazap.8m.com/aa/aa659a.jpg

1908 Quebec as 1903

1911 Admirals as 1902
http://guillermojalil.com/images/48361.jpg

US 1c special postcard rate 1916
http://filateliamk.freeservers.com/1124/9665a.jpg

1922 Admirals reissued

2c green (previously carmine), printed matter (+1c)
3c carmine (previously brown) , postcard (+1c)
8c blue (no previous 8c) letter (+3c)

1c changed to orange
5c changed to violet

1928 George V as 1922 issue

1930 issue (depression)

1c reverts to green printed matter (-1c)
2c green becomes brown
3c carmine (no change) postcard (--)
5c reverts to blue letter (-3c)
8c changes to orange

1c postcard as printed matter (short message)
http://www.southcollector.com/images/w678.jpg

1942 George VI per 1930

1949 George VI
1c remains green printed matter (--)
3c changed to violet
4c now carmine postcard (+1c)
5c remains blue letter (--)

1953 issue
1c reverts to brown
2c becomes green printed matter (+1c)
3c reverts to carmine postcard (-1c)
4c becomes violet
5c remains blue Letter (--)