Christmas Tree Lane is a 0.7-mile (1.1 km) boulevard of deodar cedar trees in Altadena, California. The trees on the Lane, Santa Rosa Avenue, have been lighted annually as a Christmas Holiday display since 1920. The association that runs it claims it is "the oldest large-scale outdoor Christmas display in the world". Christmas Tree Lane was listed on the U.S. National Register of Historic Places in 1990, the same year it was also designated as California Historical Landmark No. 990.

Santa Rosa Avenue in Altadena is one of many north–south running streets named for female Spanish saints. Others are Santa Anita, Santa Clara (becomes El Molino Avenue), and Santa Marguerita (becomes Fair Oaks Avenue). At the head of Santa Rosa Avenue was a large parcel reserved for the mansion of Altadena founder John P. Woodbury. His brother, Frederick, had already established a home at the head of Santa Clara Avenue. Santa Rosa Avenue was to be the main approach to John's mansion from the Pasadena city limit. In 1883, returning from a trip to Italy, John described an impressive stand of deodars (Cedrus deodara, the Tree of God), indigenous to the Himalayas. John returned with a handful of seeds from the trees. Having consulted with an arborist friend of his at the Department of Agriculture, who assured him the trees should do well in Southern California, he had Frederick plant them in a nursery behind his house. In two years the young trees were transplanted to Santa Rosa Avenue, in all some 150 trees.

The work on Santa Rosa Avenue was carried out by Frederick's ranch foreman Tom Hoag. This included the employment of a large Chinese labor crew not only to perform the transplanting, but also to lay the river-rock-lined gutters which have become an important part of the lane's historical landscape.^{[citation needed]}

Because of the ensuing land bust of 1888, John Woodbury's home was never realized. But the Santa Rosa deodars flourished in the decades to come.^{[citation needed]}

From 1906 to 1909, Santa Rosa was a part of the Pasadena-Altadena Uphill Race, a sport of the new high-speed automobile. Entries consisted of some of the latest race cars of the period, including the Stutz Bearcat, and Barney Oldfield's Ford No. 999. The racers rallied on Los Robles Avenue south of Woodbury and raced up to the corner, making a hard right then a hard left up Santa Rosa. The dirt roads were rugged and in one instance a female rider was tossed from the car. From that point on ladies were prohibited from riding along. The competitions only ran for four years.^{[citation needed]}

In 1920, Altadena resident and Pasadena merchant Frederick Nash, president of the Pasadena chapter of Kiwanis, convinced his fellow Kiwanians and the City of Pasadena to light the Santa Rosa deodars, now 35 years planted, for the upcoming Christmas season. That year they succeeded in lighting one-fourth of the lane. Over the next few years as the lighting grew along the lane, the number of spectators increased with many arriving by automobile to motor their way between the illuminated rows. The lane was referred to as the Avenue of the Deodars.^{[citation needed]}

In 1927 the Altadena chapter of Kiwanis formed, and annually they would take children from the local Boys and Girls Aid Society for rides along the Lane that they called "Christmas Tree Street."^{[citation needed]}

The lane was fully lit each year up until 1943 and the "switch" was pulled annually by honoree Tom Hoag, the old foreman. In 1943 the lane went unlit, but not for the war effort. That year saw a light snow pack and water for power generation was predicted to be low, so the lane was left unlit for conservation purposes. In that time Tom Hoag died.^{[citation needed]}