There is some controversy as to the earliest appearance of the Bolero.  Some historians trace it back to Spain and others trace it back to France.  It appears to have been danced as a Spanish folk dance during the 19th century, to 3/4 time music.

The American Bolero is danced to a much slower tempo than either of the other two Rumbas.  It is a little softer and flowing, with the use of a Rise & Fall action and a more subtle hip movement.  There are two different schools of thought.  One uses more rise and fall, the other uses more contra body movement.  A combination of the two may also be danced.  A lot is determined by the music and the rhythmical expression of the dancers themselves.

The Bolero, like the Rumba, is considered one of the Cuban courtship dances.  The sensual, flirtatious play can be quite intoxicating.  The Bolero is the dance of love.

Very slow, romantic and  rhythmical, hip action is minimal, with the addition of rise & fall.

Footwork:

Ball/Flat throughout, however, a more reaching action from the toes is used in advanced footwork.

Inside Edge to Flat can also be used on side moving steps.
 

*Note  1.  On side movements, the foot can roll from the inside edge of ball to a flat foot.

*Note 2.  On  "Back" Rocking steps the heel may or may not lower depending on the element used.  Also, when dancing Back Spot Turns the right "hooking" should be placed with weight on ball of  foot only.  

Tempo: 

American       24 MPM

Bolero Rhythm:
1 - 2    3  4,   1 - 2   3   4
 SL     Q  Q    SL    Q  Q

There are various other counts that can also be used with advanced elements.  Syncopations are used in more advanced variations as are holding actions on "Picture Steps".

The Rise & Fall is the advanced technique that requires strength and control, and generally years of dancing to make look poetic.  The Rise is taken softly onto the 1 - 2 counts (slow) and the Fall is on the two quicks (3 and 4 counts).

Contra Body action is created during the forward and back rocking actions.