It's about as long as The Volga
In other words, 635 leagues is 0.999 times the length of The Volga, and the length of The Volga is 1 times that amount.(a.k.a. Волга, a.k.a. İdel (Идел), a.k.a. Атăл (Atăl), a.k.a. Edil, a.k.a. İdil, a.k.a. Рав (Rav)) (from the Valdai Hills, Tver Oblast, Russia through the Caspian Sea)
The largest river in Europe, the Volga river runs 635 leagues in total length. World War II's Battle of Stalingrad between the Nazi Germany and the Soviet Union, which resulted in nearly two million casualties, was fought in part for control of the river.
It's about one-and-one-tenth times as long as The Oregon Trail
In other words, 635 leagues is 1.0 times the length of The Oregon Trail, and the length of The Oregon Trail is 0.99 times that amount.(from Independence, Missouri to Oregon City, Oregon)
The historic Oregon Trail stretched 628 leagues across five (sometimes six) states in the western United States. In the early years of the Trail's existence, the trip was estimated to have taken an average of 160 days.
It's about nine-tenths as long as The Mississippi River
In other words, 635 leagues is 0.9368 times the length of The Mississippi River, and the length of The Mississippi River is 1.07 times that amount.(from Lake Itasca, Minnesota through Pilottown, Plaquemines Parish, Louisiana)
The total length of the Mississippi River is 677.80 leagues. Prior to the development of soil erosion programs, the Mississippi River would carry approximately 400 million metric tons of sediment from its banks to the Gulf of Mexico every year.
It's about one-and-one-fourth times as long as The Danube
In other words, 635 leagues is 1.24 times the length of The Danube, and the length of The Danube is 0.806 times that amount.(a.k.a. Donau, a.k.a. Dunaj, a.k.a. Dunav, a.k.a. Duna, a.k.a. Дунав (Dunav), a.k.a. Dunărea, a.k.a. Дунáй (Dunay), a.k.a. Tuna) (from Breg Martinskapelle, Black Forest, Germany through the Danube Delta, Romania)
The Danube river runs 513 leagues in total length. Intersecting Vienna, Austria; Bratislava, Slovakia; Budapest, Hungary; and Belgrade, Serbia, the Danube touches more capital cities than any other river.
It's about four-fifths as long as The Distance from L.A. to New York
In other words, 635 leagues is 0.786 times the length of The Distance from L.A. to New York, and the length of The Distance from L.A. to New York is 1.27 times that amount.(Los Angeles, California to New York City, New York) (via I-10 E, I-15 N, I-70 E, I-76 E, I-80 E, I-280 E)
The total length of the freeway route from Los Angeles, California to New York City, New York via Interstate 80 is 808 leagues long. This route intersects eleven states and several major cities, including Las Vegas, Nevada; Denver, Colorado; Lincoln, Nebraska; Omaha, Nebraska; Des Moines, Iowa; South Bend, Indiana; and Cleveland, Ohio.
It's about three-fourths as long as I-80
In other words, 635 leagues is 0.760681 times the length of I-80, and the length of I-80 is 1.31461 times that amount.(a.k.a. Interstate 80, a.k.a. Keystone Shortway) (net length)
Interstate 80, crosses the continent of North America from Teaneck, New Jersey to San Francisco, California and covers a total length of 834.7790 leagues. A 10.79910 leagues stretch between mile marker 318 in Grand Island, Nebraska and mile marker 390 in Lincoln, Nebraska is the longest straight path in the US Interstate system.
It's about one-and-a-half times as long as The Colorado River
In other words, 635 leagues is 1.51 times the length of The Colorado River, and the length of The Colorado River is 0.662 times that amount.(a.k.a. Aha Kwahwat, a.k.a. Grand River, a.k.a. Tizon River, a.k.a. Tecon River, a.k.a. Tison River) (from Grand Lake, Colorado through the Gulf of California)
The Colorado River runs 419 leagues in length. Along this length, the river descends from its source, approximately 0.4950 leagues above sea level in the Rocky Mountains, to its mouth in the Gulf of California.