After graduating from Yale, Ehrich helped his brothers William and Jules run the Ehrich Brothers Dry Goods Store (est. 1857). Telling the "New York Tribune" that the stress of retail had left William with a "shattered constitution", Louis resigned from his own position in 1886. His health led him to relocate to Colorado Springs in 1889, where he served as vice president of the Colorado Springs and Interurban Railway company, director of the First National Bank, and president of the Board of Trade of Colorado Springs, acting in several smaller business ventures simultaneously. Along with his interest in trade and land development, Ehrich was heavily involved in politics for much of his life. Throughout the 1890s and early 1910s, he was an executive member of the Anti-Imperialist League and the Gold Democrats Party, as well as an advocate for free trade, often publishing op eds on the subject. In 1896, he was the sole delegate from the Rocky Mountain Region at the 1896 Democratic National Convention, also known as the Gold Convention of 1896. He wrote and published "The Question of Silver" to further explicate his views on the Free Silver issue. Despite his early opposition to William Jennings Bryan because of their differing opinions on the Gold Standard, Ehrich reconciled with him by the date of the 1900 election, largely thanks to Bryan's firm stance against the American annexation of the Philippines.