^Looking west from US Route 69 at Garner, September 2019.
US Route 18 is the highway spanning the second row of counties from the northern extent of the state of Iowa. It enters the state from South Dakota between Carson, South Dakota, and Inwood, Iowa. US Route 18 heads fairly straight during its eastward journey across the western half of northern Iowa, passing through Sheldon, Spencer, Emmetsburg, and Algona. At Clear Lake, US Route 18 is taken south to a different eastward highway by a concurrency along Interstate 35. A business route of US Route 18 continues east from the original highway though, carrying Iowa Route 122 along with it into Mason City. The main alignment of US Route 18 jogs south to a new eastward freeway that also carries Iowa Route 27, known as the Avenue of the Saints. (Remember that it's a freeway though, not an avenue.) Beyond Mason City, US Route 18 and Iowa Route 27 pick up US Route 218 at Floyd, and the three routes bend southward. At Charles City, US Route 18 breaks off, and US Route 218 becomes the new tagalong for Iowa Route 27. At New Hampton, US Route 18 joins US Route 63 south for seven miles to a more southerly latitude. US Route 18 reaches West Union, marking its foray into the driftless region's rugged terrain. It curves northeast to Postville, where it joins US Route 52 east. Seven miles short of leaving Iowa into Prairie du Chien, Wisconsin, US Route 52 splits from US Route 18 to head south. The final seven-mile stretch of US Route 18's eastward trek through Iowa ends with a bridge over the Mississippi River, connecting Marquette, Iowa with Prairie du Chien, Wisconsin.
My photo of US Route 18 in Iowa comes from its junction with Iowa Route 150 in West Union. The sign assembly depicted faces west, to show eastbound travelers on US Route 18 what's going on. The western beginning of Iowa Route 56 lies at a separate junction just to the south. This photo was taken in September 2019, as I was making my way across northern Iowa.
Here are some more photos taken along US Route 18 in Iowa:
Here are some more photos taken along US Route 18 in Iowa:
US Route 18 at Iowa 182 in Inwood, looking east.
US Route 18 at US Route 71 in Spencer. At this point, a westward US Route 18 begins to jog northward along US Route 71, as US Route 71's southward course is interrupted by a turn toward the west for a short while.
US Route 18 at Iowa 4, where the two routes split just west of Emmetsburg.
Looking west in downtown Emmetsburg, where US Route 18 is joined by an otherwise northbound Iowa Route 4.
US Route 18 makes a very sudden sharp right turn from its otherwise westward course in the town of Cylinder. This unique sign tries to warn about this dangerous turn.
US Route 18 at the western split with Iowa 15 near Whittemore. This photo looks west.
Looking east at the eastern split with Iowa 15 northeast of Whittemore.
US Route 18 at US Route 169 in Algona, looking west.
US Route 18 at Iowa 17's northern end near Wesley, Iowa.
US Route 69 splits from US Route 18 to continue north at Garner.
The eastern end of the short concurrency shared between US Route 18 and US Route 69, near Garner. This photo looks west.
Looking west, US Route 18 is about to join the Avenue of the Saints Expressway, or Iowa Route 27. The two routes converge to move westward toward Mason City.
US Route 18 at the south end of its concurrency along US Route 63. The signage here faces eastbound drivers at the northbound entrance ramp to US Route 63.
Looking west where US Route 18 meets Iowa 150 in West Union.
US Route 18 and US Route 52 head west from their point of convergence.
US Route 18 at the point where US Route 52 joins from the south.
US Route 18 arrives in Iowa on a bridge over the Mississippi River, and a junction marker for Iowa 76 appears to westbound travelers on this bridge. This shouts out the southern end of Iowa Route 76 in Marquette, Iowa.