The Shamrock Avenue Tract was originally part of Addition No 2 to the  Monrovia Tract (Lot A Block 18 See Addition No 2 Subdivision Map),  Brown's Addition and  Lot Block 1, Block 1 of the Pacific View Map.   Emma C. Griffith had owned the property since it had been subdivided  into Brown's Addition.  In February of 1906, she re-subdivided the  property into the Shamrock Avenue Tract.  She and her family had lived  on East Orange Avenue (now E. Colorado Ave.) since at least 1896.