- Keiffer Bros.1
- Kendall & Whitney1
- Kennedy's Celebrated Biscuit1
- Kent Brothers1
- Kerckhoff-Cuzner Mill & Lumber Co.1
- Keuffel & Esser Co.1
- Kibbe Brothers Co.5
- Knickerbocker Ice Co.1
- Konantz & Gaver Co.1
- Krohn, Feiss & Co.1
- Kuhn Netter & Co.1
- L. B. Freeman & Co.1
- L. C. Hopkins & Co.1
- L. H. Daloz1
- L. H. Smith Wooden Ware & Co.1
- L. Hatfield1
- L. J. Bensel1
- L. P. Peck1
- L. P. Smith1
- L. S. Learned1
- L. Sprague Company2
- L. W. Carroll & Son1
- L.H. Mace & Co.1
- L.M. Rumsey Mfg. Co.2
- Labsap-Crucknell Woolen Co.1
- Ladwig & Schranck1
- Lambertville Rubber Co.1
- Land Title and Trust Company1
- Landers, Frary & Clark1
- Langfeld Bros. & Co.2
- Larkin Soap M'f'g Co.3
- Lathrop, Ludington & Co.1
- Lautz Bro's & Co.1
- Lee & Bothwell1
- Lee Broom & Duster Co.1
- Lee-Coit-Andreesen Hardware Co.1
- Leeds & Hazard1
- Leon Levi, Jeweler1
- Lewis Coleman & Co.1
- Lewis DeGroff & Son Wholesale Grocers2
- Lidgerwood Manufacturing Company1
- Lincoln & Co.1
- Lindell1
- Little & Co.1
- Livingston & Co.1
- Lloyd's Plate Glass Insurance Co.1
- Lockhart & Powers Picture Frame Moulding Works1
- Longmont Farmers Milling and Elevator Co.1
- Longstreth & Brother1
- Loring, Short & Harmon2
- Los Angeles Chamber of Commerce1
- Los Angeles Company1
- Louis Stern Sons, Inc.1
- Louisville Lithographic Co.1
- Louisville Tin and Stove Company1
- Louisville Varnish Co.1
- Louisville and Old Inn Hotel1
- Lummis & Company1
- Luther Keller2
- Lyford & Woodward1