US 1 is used to travel the islands of the Florida Keys. Locations along the highway are expressed by Mile Marker numbers. The zero Mile Marker is found in Key West at the Monroe County Courthouse. Mile Marker numbers continue to increase until they pass through the Monroe County line at Mile Marker 112 north of Key Largo. Look for small green signs with white numbers posted at each mile along US1 (these used to be the original mile posts installed along the old railroad bed).

MM 87-86

Both the Rain Barrel (MM86.7) and Treasure Village (MM86.7) complexes hosts arts and craft shows, usually several throughout the year. They are great places to stop for a stretch and do a little shopping.

MM 85

Windley Key was originally two islands called Umbrella Keys because of their U shape. A land bridge connects them, so the name was changed to Windley Key, allegedly honoring an early settler. The Florida East Coast Railroad purchased the land in 1908. The FECR turned it into a quarry and began excavating large amounts of limestone to supply material for railroad embankments. No one has quarried the limestone recently but students, scientists and geology buffs often visit the Windley Key to admire and study the fossilized coral patterns exposed on the quarry walls. This is now a geological historic site, owned by the state of Florida.

MM 84

Another quarry on the ocean side of Windley Key is the site of Theater of the Sea (MM84.5), one of the oldest attractions in Florida. Opened 47 years ago, the theater offers a show starring sea creatures such as rays, turtles, sharks, sea lions and dolphins. It is also one of several locations in the Keys where you can arrange to swim with the playful bottlenose dolphins.

Whale Harbor separates Windley Key and Upper Matecumbe Key, and on both sides of the inlet, the marinas bristle with the outriggers and tuna towers of the sportfishing fleets. In this area, you'll spot the massive Holiday Isle complex, which features myriad hotels, motels, restaurants, water sports charters and other activities. Holiday Isle sponsors numerous festivals, sports and special events and celebrations throughout the year.

MM 83-81

Welcome to Islamorada's business district. Originally a farming area, the arrival of the railroad in 1906 brought development to the area. By the time the Overseas Highway opened in 1938, the area had already become a world-class fishing center and resort. At MM81.1-Bayside is Tarpon Flats, where former President Bush has visited.

MM 80-78

The Lignumvitae State Botanical Site, located Bayside at MM78.5 on 280-acre Lignumvitae Key, boasts the highest point above sea level in the Keys at 18 feet. The virgin hammock boasts more than 133 species of trees, including its namesake, the lignum vitae tree which often grows more than 1,000 years old. The wood of this tree (wood of life trees which rank among the world's hardest woods) is so dense that it has been known to outlast steel and bronze when used to outfit boats.

A coral rock house, built in 1919 by Miami pioneer, W.J. Matheson, and an adjacent 12,000 gallon cistern and windmill depicts life in that era. Park rangers conduct guided tours through the island and house. There is no road access to the island; however boat tours are available at MM77.5.

Indian Key State Historical Site, a 12-acre island, is located at MM78.5-Oceanside. In 1836 Indian Key was a thriving wrecker's village under John Jacob Housman, who made his fortune as a marine salvor. The Dade County seat was established here, but the settlement was burned to the ground in 1840, when Seminole Indians became angered by threats from Housman. The island was abandoned. Existing ruins on the island have been stabilized, and excavation of artifacts continues. Original ruins can be seen from a self-guided trail system.

In 1733, a hurricane crashed 21 Spanish galleons into Florida shores. The first of these was spotted in 1947. Not all of the wrecks have been discovered, although the most recent discovery occurred in the early 60's, when a local diver discovered the El Infante inside the reef at 30 feet. Today, divers still encounter coins and artifacts. The area has become the San Pedro Underwater Archaeological Park.

MM 77-69

Further south, next to Channel Two, (Channel Two Bridge) lies Caloosa Cove, world-famous for tarpon. Craig Key, just over 5 miles south of Indian Key, is the site of a 1733 Spanish shipwreck.

MM 68-66

Long Key State Recreation Area (MM67.5) offers picnic and camping areas, nature trail tours and canoe trips. The shallow tidal flats and mangrove-lined lagoons are home to several species of marine life, birds and other wildlife.

Leaving Craig Key for Fiesta Key, there is another area favored by tarpon as well as campers; a large campground, located at the east end of Long Key, MM66. It's no wonder that author/sportsman Zane Grey convinced Henry Flagler to convert his railroad camp on Long Key into a sportfishing lodge.

Incorporated in 1963, the city of Layton occupies 120 acres on the ocean side of Long Key and is one of three incorporated cities in Monroe County (the other two are Key West , Key Colony Beach.)

MM 65-63

The second-longest bridge in the Keys is the Long Key bridge. The building of the 2.3 mile span made use of some of the most innovative bridge-building techniques. The bridge is 12,040 feet long and connects Long Key with the Conch Key, the first of the Keys in the Marathon area.