Method of forming a plastic shopping bag having a reinforced handle

A plastic shopping bag is provided with an integral handle portion of wave configuration having a strip of reinforcement material therein of heavier gauge plastic than the remainder of the bag. The heavier gauge strip extends across the handle portion in spaced relation to the side edges of the bag. A plurality of such bags are fabricated by providing a flattened plastic film tube which has coextensive overlapping strips of heavier gauge material on the opposite faces thereof, cutting through the tube faces along a cutting line of cyclically recurring wave configuration that extends in the direction of elongation of the heavier gauge strips, the wavelength of said wave configuration being substantially equal to the desired width of the mouth of one of said shopping bags and the amplitude of said wave configuration being greater than the widths of said heavier gauge strips whereby the crests of the wave configuration are located at positions outside the boundary edges of the heavier gauge strips, and thereafter cutting the two faces along transverse seam lines which extend from the wave configuration crests to the outer edges of the flat tube of plastic film material.