Just east of the Kansas border at Carthage, Mo., 21-year-old Sarah Elizabeth Butler (1857-1931) opened her diary. Inside, she wrote eight sentences recording the first day of her trek along the Oregon Trail to Washington Territory. She loaded that entry with information, perhaps rivaling her family’s packing of their covered wagon. She told us they were still busy packing in the morning. Her sister Fannie’s husband, whom she formally referred to…