Oakland, Baltimore, Houston, Washington D.C.
Cleveland, Seattle, Pittsburgh, Toronto
St. Louis, Cincinnati, Chicago, Seattle
San Diego, Baltimore, Seattle, Toronto
Detroit, Seattle, Pittsburgh, Houston
Seattle, Detroit, St. Louis, Cleveland
Washington D.C., Seattle, Toronto, Seattle
Washington D.C., Cincinnati, Houston, Los Angeles
San Diego, Oakland, Toronto, Detroit
Cleveland, St. Louis, Seattle, Detroit
Houston, San Diego, Baltimore, St. Louis
Oakland, Cincinnati, Washington D.C., Los Angeles
Cleveland, Houston, Detroit, Seattle
San Diego, Seattle, Pittsburgh, San Diego
Oakland, Washington D.C., Cleveland, Baltimore
You can check your answers for this puzzle on
Geochecker.com.
Congratulations to fishiam for finding it first.