A 3D flash memory device includes a substrate having a substantial planar surface. A plurality of active columns of semiconducting material is disposed above the substrate. Each of the plurality of active columns extends along a first direction orthogonal to the planar surface of the substrate. The plurality of active columns is arranged in a two-dimensional array. Each of the plurality of active columns may comprise multiple local bit lines and multiple local source lines extending along the first direction. Multiple channel regions are disposed between the multiple local bit lines and multiple local source lines. A word line stack wraps around the plurality of active columns. A charge-storage element is disposed between the word line stack and each of the plurality of active columns.