1845 Preuss Map of Fremont's 2nd Expedition: Missouri to the Pacific

This is a seminal 1845 map of the American West by Carl Preuss and John C. Frémont charting the vast region between the Missouri River and the Pacific Ocean. Based on Frémont's 1843-44 Second Expedition, this map played a pivotal role in shaping westward expansion, guiding emigrants along the Oregon Trail and California Trail, and influencing cartography for decades. Wheat hailed this map as 'radically and permanently altering western cartography.' Featuring the first accurate mapping of the Great Salt Lake, detailed topographical features, and overland migration routes, this was the most comprehensive map of the American West.

A Closer Look

Frémont's map benefits from Carl Preuss's meticulous cartography and provides an expansive view of the American frontier, spanning from Westport, Kansas, to the Pacific Coast and covering present-day Missouri, Kansas, Nebraska, Wyoming, Utah, Idaho, Oregon, Nevada, and California. It documents major geographic features, including:

• The Great Salt Lake, accurately depicted for the first time, informed by Frémont's own raft navigation of its waters.
• The Oregon Trail, providing essential data for pioneers migrating westward.
• The Sierra Nevada and California Rivers, notably including the American River, central to the California Gold Rush.
• Three major Colorado River systems, mapped in detail.
• A topographical profile of the transcontinental route, running from the mouth of the Kansas River to the Pacific Ocean, a key reference for future expeditions.

As Streeter notes, 'Though the Oregon Trail and the Spanish Trail had been regularly used for a few years, there were no dependable maps. For other parts of Frémont's route, much of the recording of his map was new, including the whole extent of the Sierra Nevada Range, the California rivers from the American River south, and the three Colorado rivers.'

Historical Context

Frémont's 1843-44 Second Expedition was a turning point in American exploration. By the early 1840s, knowledge of the Rocky Mountains and Upper Missouri River Basin was relatively well-documented, but vast portions of the Great Basin, Sierra Nevada, and California interior remained uncharted. Frémont's mission, backed by the powerful Missouri Senator Thomas Hart Benton, was to scientifically survey and map the western territories, providing the U.S. government with strategic geographic data.

The resulting map had both immediate and long-term impacts. In the short term, the map became the definitive guide for westward migration, influencing emigrants on the Oregon Trail and California Trail, as well as early settlers heading toward Utah. In the long term, it shaped American territorial ambitions, played a role in the Mexican-American War (1846-1848), and influenced subsequent surveys such as the Pacific Railroad Surveys of the 1850s.

Opening the West: The Second Frémont Expedition (1843-44)

The Second Frémont Expedition began in May 1843, departing from Westport, Missouri (modern-day Kansas City). Unlike his first expedition, which focused on the Platte River and South Pass, Frémont's second journey aimed to survey the Oregon Trail in its entirety, extending into California and returning via an uncharted route across the Great Basin.

In July 1843, Frémont reached the Wind River Range in Wyoming, refining maps of the South Pass. By August, he traveled along the Snake River, documenting the Oregon Trail. In November, he entered California, crossing the Sierra Nevada via Carson Pass. During the winter of 1843-1844, he explored the Sacramento and San Joaquin Valleys, then charted an uncharted route through the Great Basin. By spring 1844, he crossed Utah and Colorado, returning to Kansas in July 1844.

Frémont's work was groundbreaking, providing crucial topographical data for future settlers. His successful navigation of the Sierra Nevada, aided by legendary guide Kit Carson, proved that California could be accessed year-round - a key revelation for future expansion.

This map specifically became the cornerstone of Western American cartography, setting the standard for most subsequent regional maps. It directly influenced the routes taken during the California Gold Rush, providing emigrants with a reliable guide. As Wheat concluded,

To Frémont and his magnificent map of his Second Expedition all praise. This is an altogether memorable document in the cartographic history of the West, and for it alone, Frémont would deserve to be remembered in history.

Publication History and Census

This map was drawn by Carl 'Charles' Preuss based on the explorations of John C. Frémont and company. It was engraved and printed by E. Webber of Baltimore, Maryland. This map was issued for both the Senate and House documents, with the Senate edition taking primacy, but between the two editions, the map itself is indistinguishable. Well represented institutionally.