The Blair Line was surveyed in the early 19th century by James "Jimmy" Blair as a boundary between Georgia and the Cherokee Nation.
 A marker in Habersham County at the junction of Georgia Highways 115 and 105, states, ""The historic Blair Line between the State of Georgia and the Cherokee Nation crossed this highway at this point.
 This line was surveyed by James Blair in the early 1800s.
 It ran from the forks of the Soque and the Chattahoochee Rivers in a direct Northerly line to the Tallulah River.
 It was the boundary line in 1817 for the purchase of all the lands East of the Chattahoochee River by the State of Georgia from the Cherokee Nation by the Treaty of 1818.""
The Fort Fairfield - Andover Border Crossing is an international border crossing between the towns of Fort Fairfield, Maine, United States, and Perth-Andover, New Brunswick, Canada on the Canada–US border, joining Maine State Route 161 (Boundary Line Road) and New Brunswick Route 190 (Fort Road).
 The United States border station was built in 1933, and was listed on the National Register of Historic Places in 2014.
 The Canada border station was built in 2007, replacing the previous facility that was built in 1954.
 This crossing was a historical flashpoint during the bloodless Aroostook War of the 1830s, in which the US and Great Britain disputed the border's location.
 That dispute was ended with the Webster-Ashburton Treaty in 1842.
New Market was a city in Scott County, Minnesota, United States.
 The population was 332 at the 2000 census.
 In January 2007, New Market merged with Elko to become Elko New Market .
 As of 2006 New Market has a public school, Eagle View Elementary School which is operated by and is part of the New Prague Schools and teaches Preschool - 5th.
The Choctaw Corner is a former Native American boundary location near the modern border between Clarke and Marengo counties in Alabama, United States.
 It was established as the northernmost terminus for a mutually agreed upon boundary line between the Choctaw and Creek peoples during the Mississippi Territory period.
 This boundary line, now known as the “Old Indian Treaty Boundary,” starts at the Alabama River cut-off in southernmost Clarke County and follows a northward path through the county along the drainage divide between the Tombigbee and Alabama rivers to the Choctaw Corner, then turns ninety degrees to the west and follows the modern county-line between Clarke and Marengo to the Tombigbee River.
Morses Line is an unincorporated community (village) in Franklin County, Vermont, United States.
 Morses Line is located on the International Boundary between Canada and the United States 5 mi northwest of Franklin.
 It is the site of the Morses Line Border Crossing connecting the towns of Franklin and Saint-Armand, Quebec.
The Coxe–Barclay Line was a boundary line or partition line drawn through the Province of New Jersey during the colonial period, dividing it into the Province of West Jersey and the Province of East Jersey.
 Surveyor General George Keith surveyed a northwesterly partition line from Little Egg Harbor that veered too far to the west, and was stopped by the order of Dr. Daniel Coxe, the governor of West Jersey.
 Keith ended his line when he reached the South Branch of the Raritan River in what is now Three Bridges in Readington Township.
 Governor Coxe, and his East Jersey counterpart, Governor Robert Barclay met in London to set a compromise boundary following the South and North Branches of the Raritan River, the Lamington (or Black) River, a straight line to the head of the Passaic River, along the Pompton and Pequannock Rivers, and then a straight line northeast to New Jersey–New York border.
 The East Jersey proprietors disowned this line in 1695 and it was formally rescinded by the colonial legislature in 1718.
Maryland Line is an unincorporated town in Baltimore County, Maryland just south of the Mason–Dixon line below York County, Pennsylvania.
 It is accessible from exits 36 and 37 off I-83.
 In the 19th century it was known as "New Market," but the name was changed to avoid confusion with a town in Frederick County with the same name.
The Mason–Dixon line, also called the Mason and Dixon line or Mason's and Dixon's line, was surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon in the resolution of a border dispute involving Maryland, Pennsylvania, and Delaware in Colonial America.
 It is still a demarcation line among four U.S. states, forming part of the borders of Pennsylvania, Maryland, Delaware, and West Virginia (originally part of Virginia before 1863).
Estcourt Station - Pohénégamook Border Crossing connects the villages of Estcourt Station, Maine and Pohénégamook, Quebec on the Canada–US border.
 The crossing is essentially a single small town divided by an international boundary.
 Several of the buildings are bisected by the boundary line.
 The US border station is located on the south end of town, where a road with access to other parts of Maine is located.
 The Canada border station is in the center of town, where the railroad underpass provides access to other parts of Canada.
 On the north end of Estcourt, there is an international pedestrian footbridge that crosses the St. Francis River.
Maryland Route 392 (MD 392) is a state highway in the U.S. state of Maryland.
 The state highway runs 13.54 mi from MD 16 in East New Market east to the Delaware state line at Reliance, where the highway continues east as Delaware Route 20 (DE 20).
 MD 392 connects East New Market with Hurlock as well as Seaford, Delaware via DE 20.
 The state highway was constructed from Finchville to Reliance in the early 1930s.
 MD 392 was extended west to Hurlock in 1951 and to East New Market in 1957.

Question: How many states does the boundary line below the New Market line border?
Answer: four