Members of the House from major metropolitan areas tend to voted overwhelmingly for the Dems. In New York State, for example, the Democrat Congressmen from NYC tend to win in absolute landslides. Upstate, however, the elections are more hotly contested. I suppose that if you gerrymanded the state to spread the NYC votes into the more competitive districts then the Dems could have all the House seats from the state of New York. But isn't that what you oppose?