In 1863 the innovation of free delivery of mail in forty-nine cities was undertaken, for which 449 carriers were employed. In 1890, 454 cities enjoyed free delivery of mail and 9066 carriers did the work. In 1921 there were about 3000 city delivery post-offices and about 36,000 carriers. The Post-office Department owns and operates almost 4000 automobiles in the collection and delivery of mail in cities, but this is a small part of the number operating under contract. The regular use of the automobile in the postal service dates back only to 1907. The feature of special delivery of mail was inaugurated in 1885. The first regular air mail route was inaugurated May 15, 1918, between Washington and New York, a distance of about 200 miles, the schedule being two hours, compared with about five hours for steam trains. [Illustration: _Airplane mail equipment._] An air route between Cleveland and Chicago was inaugurated May 15, 1919, and between New York and Cleveland July 1, 1919. The Transcontinental Air Mail Route from New York to San Francisco, inaugurated September 8, 1920, is the only route at present in operation. This coast-to-coast route is 2629 miles in length, passing through Cleveland, Chicago, Omaha, Cheyenne, Salt Lake City, and Reno. Relays of planes are used, but, contrary to the general impression, mail is not carried all the way by air; instead, planes pick up mail which has missed trains and advance it to points where it will catch through trains. Three rural routes, the first ones, were established in 1896 in West Virginia. By 1900 there were 1259; in 1906, 32,110; 1912, 42,199; on January 1, 1922, there were 44,007. Rural routes now in operation cover a total of 1,152,000 miles and the number of patrons served is about 30,000,000. The Rural Free Delivery Service brings in but about one fourth of its cost. There are also about 11,000 contract mail routes (star routes) serving communities not reached by rail or rural routes. _Postal Business Increases_ In the five years from 1912 to 1917, the increase in the volume of business as reflected by the annual gross receipts of the post-office was 33.64 per cent., and in the ten-year period from 1912 to 1921, inclusive, it was 87.84 per cent. During this decade there was a decrease in postal receipts in but one year as compared with the previous year, and that was in 1915, when the percentage of decrease was 0.23 per cent. For the ten years mentioned the percentage of increase in receipts for each year over the previous year was as follows: Percentage 1912 3.72 1913 8.65 1914 7.59 1915 .23[1] 1916 8.63 1917 5.66[2] 1918 4.47[3] 1919 5.91[4] 1920 19.81 1921 6.02 [1] Decrease. [2] Additional revenue on account of increased postage rates incident to the war not included. [3] see Footnote 2. [4] see Footnote 2. _The Post-office and Good Roads_