Why were investors in the Northern Pacific Railroad interested in expanding westward from their base of operations in Minnesota? After all, we are talking about laying nearly 2,000 miles of rail through sparsely populated lands subject to harsh weather, building bridges required to cross innumerable rivers and streams and scale the imposing heights of both the Rocky Mountains and Cascades. Who in their right mind? How about Abraham Lincoln for one. Anxious to see the country expand westward, in 1864 Lincoln signed the Pacific Railroad Act, expanding from 10 to 20 acres of land grants in alternating sections for each mile of road built and further arranged for early release of federal loans in the amount of $32,000 to $48,000 per mile of road. Not enough to cover a railroad's expenses, but seed money. That same year, Lincoln signed a land grant for the Northern Pacific - and so it began.
Armed with nearly 60 million acres of potential land grants and seed money loans, who could resist the potential of accessing the potentially rich farmlands of the upper Midwest and vast timber resources of the Pacific Northwest? Who could resist access to the bountiful deposits of high quality inexpensive coal in the Carbon River and Green River watersheds to fuel their locomotives and provide a ready customer for their transportation services. Not investors in the Northern Pacific. Following is a map showing the alternating land grants the Northern Pacific earned once Stampede Pass was completed providing a direct route to Tacoma.

Map courtesy of Washington State University, circa January 1, 1887
The darker hatched boxes are land grants. Those with black dots are federal lands. Virtually the entire area in the Enumclaw Plateau and west were either land grant lands or federally owned land. Even with seed money loans from the feds, NP investors found raising money a difficult task. Two bankruptcies later, the urgency to complete Stampede pass was urgent. Absent completing a route providing direct access to Puget Sound, these land grants would have been forfeit. Hence the NP's urgency. What did land grants sell for? Following are the NP's stated terms of sale in 1887.
The price of Agricultural Lands ranges chiefly from $2.60 to $6.00 per acre. If purchased on 5 years time, one-fifth cash. At end of first year, interest only on the unpaid amount. One-fifth of interest and principle due at end of each of next four years. Interest at 7% per annum.
On Ten Years Time - Actual Settlers can purchase not to exceed 320 acres of Agricultural Land on Ten Years Time at 7 percent interest, one-tenth cash at time of purchase and balance in 9 equal installments beginning at the end of the second year. Purchasers on the 10 year plan are required to settle on the lands purchased and to cultivate and improve the same.
Timber Lands - Cash or by special agreement.
Simple interest in their terms of sale - simpler times.