Question: According to the 2010 census, what was the population of the city on the United States side of the Four Falls Border Crossing?

Context paragraphs:
Pembina, North Dakota: Pembina is a city in Pembina County, North Dakota, United States.  The population was 592 at the 2010 census.  Pembina is located 2 mi south of the Canada–US border.  Interstate 29 passes on the west side of Pembina, leading north to the Canada–US border at Emerson, Manitoba and south to the cities of Grand Forks and Fargo.  The Pembina-Emerson Border Crossing is the busiest between Blaine, Washington and Detroit, Michigan and the fifth busiest along the Canada-United States border.  It is one of three 24-hour ports of entry in North Dakota, the others being Portal and Dunseith.  The Emerson-Noyes border crossing, located 2 mi to the east on the Minnesota side of the Red River, also processed cross border traffic until its closure in 2006.

Hyder, Alaska: Hyder is a census-designated place (CDP) in Prince of Wales-Hyder Census Area, Alaska, United States.  The population was 87 at the 2010 census.  Hyder is accessible by road, and is popular with motorists wishing to visit Alaska without having to drive the length of the Alaska Highway.  Hyder is both Alaska's southernmost and easternmost town.  There are no American border controls at the Hyder - Stewart Border Crossing.

Fort Fairfield, Maine: Fort Fairfield is a town in Aroostook County, eastern Maine, United States, located along the Canada–US border.  The population was 3,496 at the 2010 census.

El Rio, California: El Rio is a small unincorporated community in Ventura County, California, United States, on the northeast side of the 101 Freeway and Oxnard, and south of the Santa Clara River.  The town was founded in 1875 and named New Jerusalem, California by the owner of general store who became the first postmaster in 1882.  In 1885, a school and Santa Clara Catholic Church were built.  Located near where the coastal railroad line crosses the Santa Clara River, the town's name was changed to El Rio around 1900.  The former wagon river crossing route became the Ventura Freeway which separates the community from the commercial developments that grew up on the southwest side of the freeway.  That portion of the historic community and sections closer to the river have been annexed to the city of Oxnard.  Vineyard Avenue (State Route 232) is the central business district for the largely residential community.  The population was 7,198 at the 2010 census, up from 6,193 at the time the 2000 census was enumerated.  For statistical purposes, the United States Census Bureau has defined a portion of the unincorporated area as El Rio census-designated place (CDP) which does not precisely correspond to the historical community that is much larger with significant portions having been annexed to the city of Oxnard.

Hamlin - Grand Falls Border Crossing: The Hamlin - Grand Falls Border Crossing connects the towns of Hamlin, Maine and Grand Falls, New Brunswick on the Canada–US border.  The crossing is reached by Boundaryline Road on the American side and by New Brunswick Route 218 on the Canadian side.  It is the northernmost border crossing on Maine's north-south land border with New Brunswick.  In 2011, the United States replaced its border inspection facilities, which were originally built in 1964.

Great Falls, Montana: Great Falls is a city in and the county seat of Cascade County, Montana, United States.  The 2015 census estimate put the population at 59,638.  The population was 58,505 at the 2010 census.  It is the principal city of the Great Falls, Montana Metropolitan Statistical Area, which encompasses all of Cascade County and has a population of 82,278.  Great Falls was the largest city in Montana from 1950 to 1970, when Billings surpassed it.  Great Falls remained the second largest city in Montana until 2000, when it was passed by Missoula.  Since then Great Falls has been the third largest city in the state.

Klamath Falls, Oregon: Klamath Falls ( ) (Klamath: ʔiWLaLLoonʔa) is a city in and the county seat of Klamath County, Oregon, United States.  The city was originally called "Linkville" when George Nurse founded the town in 1867.  It was named after the Link River, on whose falls the city was sited.  The name was changed to Klamath Falls in 1893.  The population was 20,840 at the 2010 census.  The city is on the southeastern shore of the Upper Klamath Lake and about 25 mi north of the California–Oregon border.

Hamlin, Maine: Hamlin is a town in Aroostook County, Maine, United States.  It is located on the Canada–US border with a border crossing into Grand Falls, New Brunswick and is the closest continental location to Europe in the United States.  The population was 219 at the 2010 census.

Four Falls Border Crossing: The Four Falls Border Crossing is a one-way crossing between Fort Fairfield, Maine and Four Falls, New Brunswick on the Canada–US border.  Traffic is permitted to enter Canada at this location, but people entering the United States face arrest.

Tecate: Tecate (    ) is a small city in Baja California, Mexico, and the municipal seat of Tecate Municipality.  It is on the border with Tecate, California, United States in the San Diego–Tijuana metropolitan area.  There is a small port of entry between the sister cities that serves as a calmer alternative to the bustling port of Tijuana.  Although the city is only 64 km from San Diego, the road to the border crossing traverses mountainous terrain, reducing the viability of Tecate as an alternative to the San Ysidro Port of Entry.  As of 2010, the city of Tecate had a population of 64,764.

Supporting paragraphs: Four Falls Border Crossing Fort Fairfield, Maine
Answer: 3,496