the Congo river
Two rivers that join the Mississippi River are the Missouri River and the Ohio River.
The confluence of the Alleghaney and Monogahela Rivers form the Ohio River at Point State Park in Pittsburgh. Thus the three rivers that "come together" at that point are the Ohio, Allegahaney and Monogahela.
Ohio, Monongahela and Allegheny
Where two rivers join, this is known as the confluence.
Both the Murrumbidgee and the Darling Rivers are significant rivers which join the Murray on its northern side.
The rivers Yonne, Marne, and Oise are the main rivers joining the Seine river along its course.
The Republican and Smoky Hill rivers join at Junction City, Kansas to form the Kansas River.
the Ohio,Missouri,Arkansas, and the red river
The Monongahala River (i'm not quite sure i spelled that right), and the Allegheny River
Marañón and the Ucayali are the two rivers that join to make the amazon.
a river system
Rivers and streams that flow in to a larger river are called tributaries. They all form in the same spot.