L.A. (Los Angeles) Salsa is also "On 1". Came from 80s, absorbed some western  elements including Ballet aerial works and lifts and regarded by Latin-Americans as a theatrical ballet for the western world middle-class.

Salsa came from Cuba, Puerto Rico and Colombia in 1950's and is the #1 most popular dance in Miami night clubs today.

4 the most popular styles in USA are:

Salsa "On 2" is a New York Salsa. Dancers skip the 1st bit and make 1st step on the 2nd beat. You need to have years for music and feel the rhythm to hear that 2nd beat to start most Salsa steps. Not the best choice for the beginner.

Cali style is Colombian and has an emphasis on a speedy complicated footwork.

Ballroom Mambo is a more formal refined style of Salsa "On 2" with the emphesis on refined technique and superior elegant lines of arms, legs and body vs more relax easy look of "street" Salsa on 1.