The story more often told and, importantly, told by the city fathers of Lapwai is that it comes from the Nez Perce word “thlap-thlap,” which refers to the sound made by butterfly wings. That onomatopoeic word is a better fit, I think. It would mean the “land or place of the butterfly” or “valley of the butterfly.”
That little name holds a lot of history. It was Lapwai where Henry Harmon Spalding and his wife, Elizabeth, founded the first mission in what would become Idaho, in 1836. Elizabeth established the first school there, and became quite fluent in the native language. The Spaldings dug the first irrigation system and planted the first (wait for it) potatoes in what would become the Famous Potato state. North Idaho residents tire of being so heavily associated with potatoes, which are primarily grown in the southern part of the state, but, hey, they started it.
The first books printed in (eventual) Idaho came off the Lapwai Mission Press, the first press in the Pacific Northwest.
Fort Lapwai was operated by the military from 1862 to 1885. It was there that General Oliver Howard met with non-treaty Nez Perce on May 3, 1877 in a final attempt to head off the conflict that was then six weeks away. The Nez Perce National Historic Park is nearby at Spalding. It commemorates the history of the Nez Perce as well as their famous flight in 1877. It’s a must stop for history buffs.