为什么蓝牛仔常用橙色线缝接

The orange thread traditionally used to sew Levi Strauss blue jeans was intentionally selected to match the copper rivets（铆钉） that doubled the durability of the jeans. 

Levi Strauss, however, neither envisioned this particular use for copper riveting, which the orange thread complemented, nor the unique stitching（缝合，针脚） on the rear pockets of the jeans.

Jacob Davis, a Russian immigrant, and a tailor, who plied his trade in Reno, Nevada, formulated the idea for the riveted seam, an idea that would vastly extend the life of the jeans, and would revolutionize the garment industry. Alas, due to financial constraints, Jacob could neither afford to obtain a patent for his invention, nor to produce the new garment.

Out of necessity, Jacob approached the wholesaler（批发商） he purchased his denim（斜纹粗棉布） from with a proposal that he sell him the West Coast rights to the riveted blue jeans, in exchange for the required to obtain a patent for them. The wholesaler whom accepted Jacob's proposition was none other than Levi Strauss.

Levi gave Jacob a position with his Company in 1873 and, during his tenure, Jacob ensured that the orange thread be used in all stitching on the jeans, and that the curved, formally named "arcuate," stitches adorn the rear pockets of the jeans.

Initially the fancy, unique stitching on the rear pockets of the jeans served a purpose. The rear pockets of the first Levis the Company produced were lined with cotton, and the orange stitching prevented the padding（填料） from buckling. The Company dropped the cotton lining early on, but the stitching remained, and was registered as a trademark in 1942.

Only once did it appear as if the orange stitching on the rear pockets would become a thing of the past. The material shortage during World War II prompted Levi to contribute to the war effort by temporarily ceasing production of jeans with the trademark stitching on the rear pockets, as this was considered frivolous（无聊的，轻佻的） and wasteful. To avoid a break in continuity of the Levi tradition, the Company had the design hand painted on the rear pockets of each pair of jeans produced.

To this day, the copper rivets, matching orange thread, and ornate stitching on the rear pockets still adorn all Levis produced. The legend of Levi Strauss lives on, while Jacob Davis has been lost in the annals of history.