var viewer = new Cesium.Viewer('cesiumContainer');
var scene = viewer.scene;

var instance = new Cesium.GeometryInstance({
  geometry : new Cesium.RectangleGeometry({
    rectangle : Cesium.Rectangle.fromDegrees(-130.0, 40.0, -115.0, 60.0),
    vertexFormat : Cesium.PerInstanceColorAppearance.VERTEX_FORMAT
  }),
  attributes : {
    color : new Cesium.ColorGeometryInstanceAttribute(0.0, 0.0, 1.0, 0.8)
  }
});

viewer.entities.add({
        position : Cesium.Cartesian3.fromDegrees( -122.19, 46.1914),
        label : {
            text : 'Some Text',
            font : '24px Helvetica',
            fillColor : Cesium.Color.WHITE,
            outlineColor : Cesium.Color.BLACK,
            outlineWidth : 2,
            style : Cesium.LabelStyle.FILL_AND_OUTLINE
        }
    });

scene.primitives.add(new Cesium.Primitive({
  geometryInstances : [instance],
  appearance : new Cesium.PerInstanceColorAppearance()
}));