Why are cavalry guidons/flags red and white?

The US had Dragoons off and on from the Revolutionary War to 1821 when mounted troops were disbanded. In 1832 the Mounted Ranger Battalion was stood up, and in 1833 the Ranger Battalion went away and the US Regiment of Dragoons was stood up. Their uniform coat was dark blue, pants were sky blue and piping was yellow. Infantry at the time wore coat and pants of sky blue with white piping. Enlisted Dragoons wore a yellow stripe on their pants, Sergeants wore two stripes. Infantry enlisted got a pant stripe as a sergeant. Dragoon companies were authorized a guidon of red and white, with U.S. in white and company letter in red, no other branches had guidons. A second regiment of Dragoons was established in 1836. Regulations still stated that the guidon would have US and the company letter, however, there is evidence of some guidons having the number of the regiment. Second Dragoons. Congress being what they are, they dismounted the 2nd and made them riflemen in 1843. Then in 1844 they brought them back as 2nd Dragoons. In 1851 the uniform was changed and the Dragoons lost yellow piping and got orange piping. In 1855 the mounted arms were Dragoons (orange), Mounted Riflemen (green), and Cavalry (yellow). During the Civil War, the mounted troops were all designated as Cavalry. 1st Dragoon Regiment was designated as 1st Cavalry Regt, 2nd Dragoons became 2nd Cavalry Regt, and Mounted Riflemen became 3rd Cavalry Regt.

Artillery got guidons in 1886, Engineers got them in 1904.

The guidons or rather red and white swallow-tailed pennants were carried long before dragoons - they were carried by lancers in 17th century Europe I believe . . . They probably evolved from lances carried by knights in the middle ages and the lances had all manner of cloth pennants, from livery and heraldic colors to ladies scarfs etc.

Casimir Pulaski of Poland is the Father of the American Cavalry. He volunteered and gave his life in the American Revolution.

Because the army is loaded with anachronisms, that's why. Flags were used for signaling and organization and so each unit had easily identifiable flag, but that was in the days of horse and musket.

I don't know about the colors but Cav and Dragoons are quite different. I'm going back to the 1980's here. My 11th ACR Cav in Fulda GE had one mission, 3rd AD in Gelnhausen a different one. Traditionally Cavalry fights from the saddle, dragoons are Infantry that ride into battle and dismount.
BTW "If you ain't CAV, you ain't...."
Just joking, all soldiers are valuable.

I miss being in a CAV Unit. Something about wearing the Stetson and Spurs felt so good lol.

I was a Dragoon (5th Royal Innisikilling Dragoon Guards) and I can't think of the "red and white" association with any Dragoons. The light units were Hussars or Lancers, heavy units were Dragoon Guards

A little movie history for you . In the late 50's, i think it was 57, John Wayne and Bill Holden made a movie called the "Horse Soldiers" . Was based on the Union calvary raid on Newton station . The Cav red and white guide on's were quite visible in the movie ! For more history google up the raid on Newton station . Another good calvary raid is Mag. Gen.William Stoneman's raid . The famous song by the Band "The Night They Drove Old Dixie Down" is based on the raid .

Red for blood! Fight never surrender!

Polish heavy Cavalry dominated European battlefields in the 1500-1600s and their traditional colors were red and white. This may explain the tradition.