Q: Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Passage: Jacksonville is in the First Coast region of northeast Florida and is centered on the banks of the St. Johns River, about 25 miles (40 km) south of the Georgia state line and about 340 miles (550 km) north of Miami. The Jacksonville Beaches communities are along the adjacent Atlantic coast. The area was originally inhabited by the Timucua people, and in 1564 was the site of the French colony of Fort Caroline, one of the earliest European settlements in what is now the continental United States. Under British rule, settlement grew at the narrow point in the river where cattle crossed, known as Wacca Pilatka to the Seminole and the Cow Ford to the British. A platted town was established there in 1822, a year after the United States gained Florida from Spain; it was named after Andrew Jackson, the first military governor of the Florida Territory and seventh President of the United States. Question: What river runs alongside Jacksonville?
A:
St. Johns River