was an electrified interurban railway operating in Spokane, Washington and vicinity, extending into northern and central Idaho.

Operating in conjunction with the Graves' lines in 1903 it formed a route between Spokane and Lake Coeur d'Alene in northern Idaho.

"To increase summer and holiday ridership," historian Laura Arksey notes, "Graves and Blackwell opened beaches and amusement parks on Coeur d’Alene, Hayden, and Liberty lakes."

Blackwell and Graves, together with James J. Hill of the Great Northern Railway, pushed the interurban lines to the south into the Palouse Country, eventually reaching Colfax, Washington, and Moscow, Idaho.

In 1909, two Spokane and Inland Empire trains collided head on at Gibbs, Idaho (near Coeur d'Alene) killing 16 people and injuring over 100.

The only S&IE piece of equipment left is a lone boxcar at the Inland Northwest Rail Museum in Reardan, WA.