In August 1933, state authorities unveiled a plaque at the dedication of a new Conde McCullough-designed bridge on State Highway 164, spanning the Santiam River at Jefferson. The plaque memorialized Jacob Conser, an 1848 Oregon Trail migrant who played a significant role in Marion County history during the 1850s. Conser founded two towns, established an important ferry crossing of the Santiam, served in the legislature for Linn and Marion Counties, and stood as Marion County commissioner from 1850 to 1853.

Conser was born in Union County, Pennsylvania, in 1818, the first in a large family. As often happened in large families, his parents bound him out to a farmer in Center County, Pennsylvania, when he reached his teenage years. Conser’s experience did not sit well, so at age nineteen Jacob broke his indenture and fled to Knox County, Illinois. There he applied a limited training he had received in millwork, made a modest wage, and met and married Nancy Gunsaulus in 1839.

In 1848, Jacob and Nancy Conser and their two children traveled the Oregon Trail. When they arrived at The Dalles, the season was too late to complete their journey by taking the Barlow Road around Mount Hood to Oregon City. So, Conser broke down his wagon, built a raft, and descended with his family to Cascade Rapids, while his stock was trailed down the south side of the Columbia. At the Rapids, the stock swam across the river to the north, where he put his wagon together, loaded it up, and drove it around the rapids. At the lower Cascade, he broke down the wagon yet again, and ferried his belongings, by way of a Hudson's Bay Company bateau, to safety below the Sandy River Delta. The stock then made a second crossing of the river, where Conser collected them near the delta. After finally arriving in Oregon City, the family took up residence at the forks of the Santiam River near Scio. The Consers would eventually have ten children, eight born in Marion County.

Conser’s experience in millwork served him well in Oregon. After one season at Santiam Forks, he moved downriver to Santiam City, where he established a sawmill in 1849. Santiam City, however, was susceptible to flooding—a flood in 1861 practically wiped out the town—so Conser took up a 320-acre claim in 1850 at the site of Jefferson, upriver from Santiam City.

At Jefferson, Conser joined with James Bates, whose land claim abutted his, to build a substantial mill and millrace, which diverted Santiam water about two miles upriver from the town site. Conser also established a ferry at Jefferson, which quickly became the main crossing on the Santiam for wagon traffic south from Oregon City. By 1852, Jefferson had become the principal town on the river. Conser made his ferry on the Middle Santiam free to all travelers in September 1854.

Conser contributed substantially to building Jefferson, including the donation of land in 1856 for the Jefferson Institute, a private school for local children that emphasized classical education and continued until the formation of a public school district in 1899. He also participated in elective politics, serving as a Democrat in the Territorial Council in 1849 and in the House from 1852 to 1857. He was Marion County commissioner from 1850 to 1853, and he was Jefferson’s mayor from 1870 through 1872, once the town received a municipal charter from the state in 1870. Conser was also an incorporator of the Oregon Central Railroad Company in 1867. His home, built in 1854, was Jefferson’s most substantial early residential building and served for many years after his death, first as the Jefferson Hotel and then as the town’s city hall. Today, it houses the city library.

Nancy Conser died in 1879. Conser married Elizabeth Humphrey of Eugene in 1881, whom he had known as a youth in Pennsylvania. He moved to Eugene in 1881, where he lived out his life until his death in 1893.