Conic projections project the sphere onto a cone, and then unroll the cone onto the plane. Conic projections have two standard parallels.
Source · The conic conformal projection. The parallels default to [30°, 30°] resulting in flat top.
Source · The Albers’ equal-area conic projection.
Source · The conic equidistant projection.
Source · This is a U.S.-centric composite projection of three geoConicEqualArea projections: geoAlbers is used for the lower forty-eight states, and separate conic equal-area projections are used for Alaska and Hawaii. The scale for Alaska is diminished: it is projected at 0.35× its true relative area. See Albers USA with Territories for an extension to all US territories, and d3-composite-projections for more examples.