Article: Major reductions in the cost of lighting occurred with the discovery of whale oil and kerosene. Gas lighting was economical enough to power street lights in major cities starting in the early 1800s, and was also used in some commercial buildings and in the homes of wealthy people. The gas mantle boosted the luminosity of utility lighting and of kerosene lanterns. The next major drop in price came about with the incandescent light bulb powered by electricity.

Question: When did gas powered street lights became economically available.
early 1800s