Loveland grew through a series of shifts in settlement and economy that began with Mariano Medina's toll bridge and trading post on the Big Thompson River in 1858. Built along what would become the Overland Trail, Medina's crossing was among the first settlements in the region. When the pioneer trail moved three miles east in 1864, settlers followed and gathered around Andrew Douty's flour mill in a town called Old St. Louis. In 1877, another move came with the arrival of the Colorado Central Railroad, whose owner, W.A.H. Loveland, routed the tracks over the land of his friend David Barnes; Barnes founded a town there and named it for Loveland, creating present-day Loveland. At first a small agricultural town, Loveland became a city after the Great Western Sugar Company built a plant there in 1901. The factory employed hundreds, provided local farmers with a profitable market for sugar beets, and drew successive immigrant labor forces, first Germans from Russia, then Japanese and Hispanos, into the beet fields. Great Western dominated the local economy until 1960, when Hewlett-Packard opened a plant that became the community's largest employer and helped create a thriving technology sector. Loveland also became known for an ambitious public art program and for its Valentine's Day tradition, when millions of cards are sent there each year to receive the city's distinctive "America's Sweetheart" postmark.