Here is a list of the world's longest rivers. The list and the distances seem to change from year to year as geographers decide whether to include or not include certain tributaries and streams. Caveat emptor!

#	River	Length (miles)	Length (km)	Flows into
1	Nile	4,145	6,673	Mediterranean Sea
2	Amazon	4,000	6,440	Atlantic
3	Mississippi-Missouri	3,740	6,021	Gulf of Mexico
4	Yangtze	3,720	5,989	China Sea
5	Yenesei-Angara	3,650	5,877	Arctic
6	Amur-Argun	3,590	5,780	Sea of Japan
7	Ob-Irtysh	3,360	5,410	Arctic
8	Plata-Parana	3,030	4,878	Atlantic
9	Yellow	2,903	4,674	Yellow Sea
10	Congo	2,900	4,669	Atlantic
11	Lena	2,730	4,395	Arctic
12	MacKenzie	2,635	4,242	Arctic
13	Mekong	2,600	4,186	South China Sea
14	Niger	2,600	4,186	Atlantic
15	Missouri	2,533	4,078	Mississippi River
16	Mississippi	2,348	3,780	Gulf of Mexico
17	Murray-Darling	2,330	3,751	Indian
18	Volga	2,290	3,687	Caspian Sea
19	Madeira	2,013	3,241	Amazon River
20	Sao Francisco	1,988	3,201	Atlantic
21	Yukon	1,979	3,186	Bering Sea
22	Rio Grande	1,885	3,035	Gulf of Mexico
23	Purus	1,860	2,995	Amazon River
24	Lower Tunguska	1,860	2,995	Yenesei River
25	Indus	1,800	2,898	Arabian Sea
26	Danube	1,776	2,859	Black Sea
27	Brahmaputra	1,770	2,850	Ganges River
28	Salween	1,750	2,818	Bay of Bengal