Flanders, Elsberg, Herber & Dunn, LLC is one of the oldest law firms west of the Mississippi and likely the oldest Colorado firm in continuous existence. The law firm was formed in 1871 by Col. Byron L. Carr (1842-1899) and Charles E. Day (18__-1911). The law firm became Carr and Secor in 1882 after F. P. Secor (1852-1930) read for the law under the supervision of Col. Carr.

The law firm was initially located in the St. Vrain Hotel on the east side of the 300 block of Main Street in Longmont. When the building burned to the ground in 1879, the firm then relocated to the More and Dell Building. The law firm later relocated to other buildings around Longmont including, the Union Block Building, 369 Main Street, 321 Main Street, the Cor and Bardill Building, and then to 323 Main Street. In 1964, the law firm relocated to its current location at 401 Main St. Suite 1 in the Independent Financial Building.

Throughout the law firm's 149 year history, the core philosophy has been to provide the highest quality legal services in personal injury, estate planning and administration, civil litigation, family law, creditor/debtor, employment, criminal defense, tax, real estate, water and business.