Lapwai is a city in Nez Perce County, Idaho, United States. Its population was 1,137 at the 2010 census, and it is the seat of government of th…Lapwai is a city in Nez Perce County, Idaho, United States. Its population was 1,137 at the 2010 census, and it is the seat of government of the Nez Perce Indian Reservation. The area that is today Lapwai was the home of Hin-ma-tute-ke-kaikt, also known as Big Thunder and later as James. It was here that Henry Spalding established a Protestant mission among the Nez Perce in 1836. This was also the general region that Bill Craig settled, since his wife was James' daughter.