A few miles to the west, US 23 meets with US 1/SR 15 (Martin Luther King Jr. Parkway), becoming concurrent with the highway through the rest of its journey through Florida.

At Callahan, US 1/US 23 meets with US 301, beginning a three-way concurrency as the road continues northward toward the St. Marys River, leaving Florida and entering Georgia.

In Hazlehurst, US 23 intersects US 221 and begins running concurrently with US 341, a divided four-lane highway designated the Golden Isles Parkway.

The highway runs concurrent with US 441 between the Georgia state line and Dillsboro, then with US 74 through Waynesville as the Great Smoky Mountains Expressway, followed by US 19 through Canton and Enka–Candler.

US 23 runs concurrently with the newly upgraded I-26 from the North Carolina state line past Johnson City and Kingsport.

Loretta Lynn, Dwight Yoakam, Billy Ray Cyrus, Patty Loveless, Crystal Gayle, Chris Stapleton, Hylo Brown, and more are all noted along US 23's path through Kentucky.

From here, US 23 passes the Ashland Town Center Mall and the Melody Mountain shopping district before exiting the city limits.

Continuing north near Bellefonte, the highway passes AK Steel's Ashland Works then enters Greenup County.

Since 1999, the entire Kentucky portion is a four-lane divided highway; in some of the larger cities, there are additional traffic lanes present in both directions.

In northeastern Kentucky, from the I-64 junction north into Ohio, some sections are four-lanes undivided, with a double yellow line instead of a median.

The majority of US 23 in Ohio is a divided expressway, with the exception of downtown Columbus and the portion of the route between Carey and US 20 east of Perrysburg.

US 23 crosses the Ohio River from Kentucky, enters Portsmouth, and passes through the towns of Lucasville, Piketon, Waverly, Chillicothe, and Circleville, before reaching Columbus.

US 23 then follows High Street northbound from Columbus, going through Worthington, passing the village of Lewis Center, entering Delaware at the Cheshire Road intersection.

After US 23 intersects the northern terminus of State Route 315 (SR 315) and passes a retail district, it becomes a limited-access freeway, bypassing downtown Delaware, before resuming as an expressway with at-grade crossings north of the city.

It continues as a freeway throughout most of Marion County, then resumes at-grade crossings with a mix of some freeway-style junctions which are otherwise signalized after the Morral interchange.

SR 15 continues on to Findlay and is designed to allow most traffic to bypass the northern stretch of US 23 by offering a fast connection to I-75.

The combined freeway passes to the west of Flint, sharing an interchange with I-69, before continuing north toward Saginaw and Bay City.

As a result, on February 10, 1824, James Kilbourne of the Ohio House of Representatives introduced a petition to revise and correct the state road leading from Columbus and Worthington to Delaware, Norton, and further north.

Kilbourne believed that the Sandusky Bay was the perfect place for a harbor to open up the Ohio marketplace to New England.

He laid out a southern extension of the road to tie Portsmouth on the Ohio River to the central and northern parts of the state.

The following year, the federal government gave 31,840 acres (12,890 ha) in trust to the state of Ohio for the turnpike company to finance road improvements and development.

Angry at the poor, muddy condition of the road, particularly in the rainiest seasons, travelers occasionally destroyed tollgates.

The Columbus and Sandusky Turnpike Company was disbanded February 28, 1843, when the Ohio legislature repealed the act that incorporated it.

In 1985, US 23 was upgraded to Interstate standards on the initiative of Eddie Williams, chief executive officer of economic development for Johnson City, Jonesborough, and Washington County, Tennessee.

"The original idea for that project happened in 1985, when two young men [later named as Don Kiel and Alan Bridwell] walked into my office with a plan to upgrade Highway 23 to interstate standards", Williams said.

[11] On March 1, 1994, a bill sponsored by State Representative Hubert Collins was passed by the Kentucky General Assembly.