One-piece lock-back lid

A drink-through plastic lid for drink cups comprising:

• a circular rim adapted to fit onto the rim of a cup;
• a raised crown defining a generally annular deck above said rim and radially spaced inwardly therefrom;
• a drink-through opening formed in said deck;
• a thin flexible flap having an integral hinge connecting said flap to said crown immediately inwardly adjacent said opening whereby the flap is pivotable toward the center of the lid to open and close said opening;
• said flap having side edges
• a seal lip formed on a surface of said flap to coact with part of the inside edge of said opening to latch the flap in the opening and seal the opening when latched;
• and
• a latch-back recess formed in said lid having opposing side surfaces, said side surfaces being shaped and spaced apart to latchingly receive the side edges of said flap in a folded-back position and latch said flap in said folded-back position wherein the flap is positioned substantially into said well;
• said lid further including a well within said crown and having a floor below the plane of said deck;
• wherein the well is stepped to define a generally annular intermediate deck above said floor but having at least a portion which is below the level of said annular deck, said latch recess forming a gap in said intermediate deck.