Originally Posted by fireman0174

In 1976/1977 United closed the Newark pilot base and moved the flying and crews to Cleveland. The flight crew base at JFK/LGA remained open and they covered Newark flying when needed after the EWR base closure.

A trip sequence after this date (1976/1977), that originated and terminated at EWR and flown by pilots based at JFK/LGA, triggered "double town" pay which is, I believe, what you're referring to.