The prosperity of Portland and the development of the Columbia River Basin depended on efficient transportation on the river. Unlike the great rivers of the East, the Columbia had numerous obstacles to navigation such as falls, rapids, and shoals. Steamboats hauled freight and passengers as far as the barriers, where everything and everyone was transferred to portage railroads. Freight between Portland and the mines of Idaho had to be handled as many as 14 times and since the Oregon Steam Navigation (OSN) Company owned the portages, it monopolized business and set rates. Gold discoveries in eastern Oregon and in Idaho and the realization that the interior held great potential for dryland wheat farming made improvement of the Columbia imperative.
The U.S. Army Corps of Engineers bore responsibility for improving and maintaining waterways. Lobbying by Portland business interests and Oregon politicians got Congress to fund a survey of the Cascades rapids, 45 miles east of Portland. The motive of the proponents of river improvements was to break the OSN's monopoly on river traffic, but the OSN was also interested in the safety of its steamboats.
Congress approved a survey in 1874, and additional monies in 1876 to start construction on two 300-foot-long locks and a 7,200-foot canal on the Oregon side of the rapids. The project struggled for the next 20 years, first under the direction of a contractor, then under direct Corps of Engineers management, and finally under another contractor. For six of the years, Congress neglected to appropriate any money whatsoever, and progress stalled until funding returned. Before work could begin on the canal and locks, the river above and below the rapids had to be dredged and improved.
Labor problems plagued the project because of poor working and living conditions and the magnitude of the task. In bad weather, men wore waterproof clothing and heavy boots, which cut their productivity in half. Annual rainfall averaged 78 inches, and during two winters 12 feet of snow covered the work site. Some seasons, low water forced work to stop and employees were paid off. The project had to be reconstituted when conditions permitted.
Until 1891, the workforce rarely exceeded 200. The town of Cascade Locks, Oregon, grew up around the site, with about 100 permanent residents. Contrary to criticism from contractor interests, the Corps was able to derive great efficiency from its direct management of procurement and construction. This did not stop Congress in 1891 from ordering the Army to hire a contractor to finish the long-delayed project. The flood of 1894 delayed work even further.
In 1896, the two locks and canal were ready. The canal was eight feet deep, 50 feet wide, 300 feet long, and 1.4 miles long with a concrete floor and walls. A set of guard gates upriver designed to allow servicing of the main lock gates could be used as an additional lock during high water conditions. The addition of concrete to the canal and the use of steel for the lock gates, not to mention the delays and complications in construction, tripled the original cost estimates to more than $3.7 million.
On November 5, 1896, Portland residents boarded the steamer Sarah Dixon and passed through the locks. A small cannon boomed salutes. With competition from rail rates moderated, agriculture and mining in the interior flourished. In 1905, 1,417 boats transited the canal up and down river. In 1915, the Corps finished its improvements at The Dalles and steamboats could reach Lewiston, Idaho, from Astoria, Oregon.
In 1938, the spill gates of Bonneville Dam closed and the impounded river inundated the Cascade Locks. The locks at Bonneville took over navigation up the Columbia.