Every once in a while, it strikes me as odd that "red" has come to mean "right wing" in U.S. politics. From this morning's headlines: "Election 2010: Things are starting to look red";"Republicans make it a red November"; "River of Red Buries the Blue"; "Hoosier State Turns Red"; "Republican red tide seeps into Maryland"; "California Voters Turn Back the Angry Red Tide".
The OED's sense A.17. for red is glossed "Originally: revolutionary; republican; anarchistic. Later: communist, socialist; spec. of or relating to the Soviet Union". The citations, ironically, begin with a reference to the "Red Republicans" of the 1848 Paris uprising:
1848 Illustr. London News 1 July 415/1 The ‘Red Republicans’ have justified their name. They have filled the streets of Paris with blood. [1849 Tait's Mag. 16 402/2 Germany itself is red with Socialism and a desire for Republicanism.] 1864 Spectator 16 Apr. 443/2 England is not Red..but she does sympathise heartily with Garibaldi's immediate ends. 1883 Pall Mall Gaz. 2 Feb. 1/2 The Dynamitards have not secured the return of a single deputy even for the ‘reddest’ constituency in France. 1920 Blackwood's Mag. Sept. 404/2 The Red Government, still bent upon the destruction of Europe, was..recognised. 1927 W. E. COLLINSON Contemp. Eng. 85 The spread of the Bolshevistic propaganda has led to the fear, lest Labour should go red. 1958 Spectator 6 June 723/2 There are still hundreds of writers in gaol all over the Red Empire. 1995 R. JEFFREYS-JONES Changing Differences vii. 110 Within a short space Smith had been depicted as a scarlet woman and as a Red politician..
Similarly, the noun sense B.15. is "Originally: a political radical, as a republican, anarchist, or socialist. Now chiefly: a communist; a radical socialist; spec. (now hist.) a Russian Bolshevik; a citizen or supporter of the Soviet Union":
1851 Punch 20 245/2, I dreamt that I stood in the Crystal Halls, With Chartists and Reds at my side. 1858 Harper's Mag. Apr. 704/2 The Reds rejoice in that measure of distress which can be relieved only by the guillotine. 1892 MRS. H. WARD David Grieve II. 349 My father was a Red — an Anarchist. 1928 D. L. SAYERS Lord Peter views Body iii. 44 I'm a Tory, if anything. I'm certainly not a Red. 1957 Economist 7 Dec. 882/2 Dr Villeda..has been at pains to show the Americans that he is no red. 1976 C. BERMANT Coming Home I. i. 16 There came the depredations of the Russian civil war, first from the Reds then the Whites. 2001 J. ELLROY Cold Six Thousand cii. 553 He don't take no shit from the Reds in Vietnam.
And then there's the anthem of the Red Guards era in China, 东方红 ("The East is Red"):
The east is red, the sun is rising.
China has brought forth a Mao Zedong.
He works for the people's welfare.
Hurrah, He is the people's great savior!
Not to speak of "The Red Flag", which is more about conviction in the face of sacrifice than any particular political ideals, but has traditionally been the anthem of the British Labour Party:
The people's flag is deepest red,
It shrouded oft our martyr'd dead
And ere their limbs grew stiff and cold,
Their hearts' blood dyed its ev'ry fold.
Then raise the scarlet standard high,
Within its shade we'll live and die,
Though cowards flinch and traitors sneer,
We'll keep the red flag flying here.
Ben Zimmer did his usual authoritative job of surveying the history here:
…the networks arrived at a formula for assigning colors to political parties for election-night coverage so that there would be no perception of favoritism in the color coding. Since 1976, the color of the incumbent party has alternated […]
Because of this system, it just so happens that Democrats were assigned the color red and Republicans blue five out of six times between 1976 and 1996. But 2000 and 2004 had blue for Democrats and red for Republicans, and those have been the election years in which the "red state" vs. "blue state" distinction has been popularized.
It's hard to believe that something so reflexive is so recent, but apparently it is.