Kerosene lighting was much more efficient and less expensive than vegetable oils, tallow and whale oil. Although town gas lighting was available in some cities, kerosene produced a brighter light until the invention of the gas mantle. Both were replaced by electricity for street lighting following the 1890s and for households during the 1920s. Gasoline was an unwanted byproduct of oil refining until automobiles were mass-produced after 1914, and gasoline shortages appeared during World War I. The invention of the Burton process for thermal cracking doubled the yield of gasoline, which helped alleviate the shortages.