About three miles (4.8 km) later, I-840 crosses the Natchez Trace Parkway and gradually turns east, continuing through similar terrain.

It then crosses into Rutherford County, entering a more flat terrain and another suburban area, and, about eight miles (13 km) later, I-840 comes to an interchange with I-24 northwest of Murfreesboro.

About 0.75 miles (1.21 km) later, I-840 crosses the west fork of the Stones River, gradually turning northwest.

The route then turns northeast and, about 3.8 miles (6.1 km) later, reaches its eastern terminus with I-40 west of Lebanon.

[5][6] The route that is now I-840 had its origins in the 1975 Tennessee Highway System Plan issued by TDOT for the next four years, which first identified the need for an outer beltway around Nashville by 1995.

[3] Planners considered using SR 396, a short controlled-access connector between US 31 and I-65 in Spring Hill, for part of I-840, but ultimately chose a location about six miles (9.7 km) to the north.

[22][23] Due to high costs and environmental concerns, the proposed northern half of I-840 was indefinitely placed on hold in 2003.

[11] As work moved into predominantly rural southwestern Williamson County, however, a group of landowners opposed to the route began a movement to stop its construction in 1997.

[26][27] Between the late 1990s and mid-2000s, these landowners, spearheaded by singer-songwriter Gene Cotton, filed complaints and eventually lawsuits in an effort to have TDOT address both environmental and aesthetic issues, considerably slowing work on the segment between SR 100 and US 31.

[29] As a result of these lawsuits, TDOT chose to slightly modify the design and employ new construction methods on the remaining sections the following year.

[3] These changes included construction of bridges over streams feeding the South Harpeth River instead of culverts; multiple wildlife underpasses; and designation of the remaining sections as a scenic highway, which prohibits billboards and uses brown powder-coated guardrail.

[31] On February 9, 2006, TDOT announced that the realignment of the final segment of I-840 had been chosen and that work on the unfinished sections would proceed.

[11] TDOT was first authorized to begin studies for a northern loop of I-840 north of Nashville and past Dickson, Clarksville, Springfield, and Gallatin by the state legislature in 1993.

[7] Other important objections against additional extensions of I-840 include the hilly nature of the terrain north of Nashville (the Highland Rim), which would require huge and costly amounts of excavation, soil relocation, and bridge construction.

[1] The western terminus of I-840 contains a very short unused extension, constructed in anticipation of the northern segment.

[44] Since 2007, the state has named bridges on I-840 in honor of members of the Tennessee National Guard killed in the global War on Terror.