It's about four-fifths as long as The Rhine.
In other words, 661 miles is 0.8060 times the length of The Rhine, and the length of The Rhine is 1.240 times that amount.(a.k.a. Rhein, a.k.a. Rijn, a.k.a. Rhin, a.k.a. Rain, a.k.a. Reno, a.k.a. Rhenus, a.k.a. Ryn) (from near Reichenau, Switzerland through Hoek van Holland, Rotterdam, Netherlands)
The Rhine river runs 820 miles in total length. The World War II Battle of Arnhem, as memorialized in the 1974 book and 1977 movie A Bridge Too Far, was the first of several attempts to capture key bridges across the Rhine, beginning with the Arnhem Bridge in the Netherlands.
It's about half as long as The Colorado River.
In other words, 661 miles is 0.4570 times the length of The Colorado River, and the length of The Colorado River is 2.190 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 1,450 miles in length. Along this length, the river descends from its source, approximately 1.710 miles above sea level in the Rocky Mountains, to its mouth in the Gulf of California.
It's about two-and-a-half times as long as The Grand Canyon.
In other words, 661 miles is 2.390 times the length of The Grand Canyon, and the length of The Grand Canyon is 0.4180 times that amount.(a.k.a. Gran Cañón) (Arizona) (Colorado River miles measure)
The Grand Canyon has a total length of 277 miles along the course of the Colorado River at its bottom. Having opened in early 2007, the Grand Canyon Skywalk allows tourists to stand on a horseshoe-shaped glass walkway 0.6840 miles above the floor of Granite Gorge.
It's about two-fifths as long as The Danube.
In other words, 661 miles is 0.3730 times the length of The Danube, and the length of The Danube is 2.680 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 1,770 miles 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 three-tenths as long as The Oregon Trail.
In other words, 661 miles is 0.3050 times the length of The Oregon Trail, and the length of The Oregon Trail is 3.280 times that amount.(from Independence, Missouri to Oregon City, Oregon)
The historic Oregon Trail stretched 2,170 miles 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 three-tenths as long as The Volga.
In other words, 661 miles is 0.3010 times the length of The Volga, and the length of The Volga is 3.320 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 2,190 miles 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 three-tenths as long as The Mississippi River.
In other words, 661 miles is 0.28250 times the length of The Mississippi River, and the length of The Mississippi River is 3.540 times that amount.(from Lake Itasca, Minnesota through Pilottown, Plaquemines Parish, Louisiana)
The total length of the Mississippi River is 2,340 miles. 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.