Question: The Mortimer Webster House is a historic house in Stillwater, a city in Washington County, Minnesota across the St. Croix River from the state of Wisconsin, in which country?

Context articles: Saint Croix National Scenic Riverway
St. Croix Chippewa Indians
Sunrise River
Mortimer Webster House
Stillwater, Minnesota
St. Croix Bluffs Regional Park
Willow River (St. Croix River)
State Highway 243 (Minnesota–Wisconsin)
St. Stephen, New Brunswick
Stillwater Bridge (St. Croix River)

The Saint Croix National Scenic Riverway is a federally protected system of riverways located in eastern Minnesota and northwestern Wisconsin.
 It protects 252 mi of river, including the St. Croix River (on the Wisconsin/Minnesota border), and the Namekagon River (in Wisconsin), as well as adjacent land along the rivers.
 The St. Croix National Scenic Riverway is one of the original eight National Wild and Scenic Rivers, largely as a result of legislation by senators Walter Mondale of Minnesota and Gaylord Nelson of Wisconsin.
 The largest scenic riverway east of the Mississippi River, it lies within parts of eight counties in Wisconsin: Bayfield, Burnett, Douglas, Pierce, Polk, St. Croix, Sawyer, and Washburn; and three in Minnesota: Chisago, Pine, and Washington.
The St. Croix Chippewa Indians (Ojibwe language: "Manoominikeshiinyag", the "Ricing Rails") are a historical Band of Ojibwe located along the St. Croix River, which forms the boundary between the U.S. states of Wisconsin and Minnesota.
 The majority of the St. Croix Band are divided into two groups: the federally recognized St. Croix Chippewa Indians of Wisconsin, and the St. Croix Chippewa Indians of Minnesota, who are one of four constituent members forming the federally recognized Mille Lacs Band of Ojibwe.
 The latter is one of six bands in the federally recognized Minnesota Chippewa Tribe.
The Sunrise River is a 39.1 mi tributary of the St. Croix River in east–central Minnesota in the United States.
 It is formed at the city of Forest Lake in Washington County at the outlet of Forest Lake.
 The river flows north, accepting the South Branch from the west near the city of Wyoming, and continues north into Mud Lake, where the West Branch, which rises in southeast Isanti County and briefly enters Anoka County, joins it near the city of Stacy.
 From Stacy it flows generally north-northwest through Chisago County to meet the St. Croix River within Wild River State Park near the communities of Sunrise and Almelund.
 Not far upstream from its mouth, the Sunrise collects its North Branch, which rises in Isanti County and flows through the city of North Branch.
The Mortimer Webster House is a historic house in Stillwater, Minnesota, United States, constructed 1865–1866.
 It is listed on the National Register of Historic Places in 1982 for having local significance in the themes of architecture and commerce.
 It was nominated for being one of the best examples of Italianate architecture in Stillwater, and for its association with Mortimer Webster, one of the town's notable early entrepreneurs.
Stillwater is a city in Washington County, Minnesota across the St. Croix River from the state of Wisconsin.
 The population was 18,225 at the 2010 census.
 It is the county seat.
 Stillwater is part of the Twin Cities Metro Area.
Saint Croix Bluffs Regional Park is a 579-acre park in Washington County, Minnesota.
 Located just outside Denmark Township on the Saint Croix River, the park is the southernmost public park on the Saint Croix National Scenic Riverway.
 St. Croix Bluffs Regional Park on St. Croix Trail opened in 1996 on a site purchased and developed in the 1940s by architect Thomas Ellerbe, later the Control Data Corporation employee park.
 It is one of seven regional parks in Washington County.
 The park has rolling prairies, wooded ravines, and scenic bluffs.
 It is managed by the Minnesota Department of Natural Resources.
The Willow River is a 61.1 mi river in St. Croix County, Wisconsin, United States, and a tributary of the St. Croix River.
 Its source is in southern Polk County east of the village of Clear Lake.
 The river at one time flowed unobstructed into the lower St. Croix River in between Hudson and North Hudson ( ).
 But a dam was built to block off its mouth, a narrow channel was cut above the dam to the St. Croix River, the channel was dammed, and a mill was built to exploit the head of water that the two dams created.
 Subsequently, the Willow River Power Co. built a hydroelectric facility to utilize the same head of water, but the head was substantially decreased when the United States built the Red Wing Dam 30 miles downstream on the Mississippi River.
Trunk Highway 243 and State Trunk Highway 243 (MN 243, WIS 243) are two short state highways in the U.S. states of Minnesota and Wisconsin.
 They connect MN 95 in Franconia Township, Minnesota with WIS 35 in Osceola, Wisconsin.
 The two highways meet at the state line on a bridge across St. Croix River.
 The combined highway is 1.53 mi in length, 1.23 mi in Minnesota and 0.30 mi in Wisconsin.
 The two highways were designated in 1949.
 The bridge across the St. Croix River dates to 1953.
St. Stephen (2011 population: 4,817) is a Canadian town in Charlotte County, New Brunswick, situated on the east bank of the St. Croix River around the intersection of New Brunswick Route 170 and the southern terminus of New Brunswick Route 3.
 The St. Croix River marks a section of the Canada–United States border, forming a natural border between Calais, Maine and St. Stephen.
 U.S. Route 1 parallels the St. Croix river for a few miles, and is accessed from St. Stephen by three cross-border bridges.
The Stillwater Bridge (alternatively known as the Stillwater Lift Bridge, St. Croix River Bridge at Stillwater, Mn/DOT Bridge #4654, and Wis/DOT Bridge #M-61) is a vertical-lift bridge crossing the St. Croix River between Stillwater, Minnesota, and Houlton, Wisconsin.
 It formerly connected Minnesota State Highway 36 and Wisconsin Highway 64.
 Around 18,000 vehicles crossed the bridge daily.
 The new St. Croix Crossing bridge crossing the St. Croix river valley to the south of Stillwater replaced its purpose, having opened to highway traffic on August 2, 2017, leaving the