Washington/Baltimore through Philadelphia to New York City and onto Boston.
London through Oxford (University) to Birmingham to Manchester and onto Glasgow.
Detroit/Windsor (via London Ontario) to Toronto to Ottawa via Kingston (Queens University) onto Montreal.
Narrow inter-city transportation corridors connecting a linear series of big metropolitan cities, each with massive demographic, industrial, financial, media and academic power --- in the formal sense of the geographers.
As well as the site of the intimately closely knit exclusive 'corridors of power', aka today's 'Beltway', in the more informal sense of lobbyists and journalists....