Question: Immigrant farm workers during the Dirty Thirties used a route that connected what states?

Context paragraphs:
United Farm Workers: The United Farm Workers of America , or more commonly just United Farm Workers (UFW), is a labor union for farmworkers in the United States.  It originated from the merger of two workers' rights organizations, the Agricultural Workers Organizing Committee (AWOC) led by organizer Larry Itliong, and the National Farm Workers Association (NFWA) led by César Chávez and Dolores Huerta.  They became allied and transformed from workers' rights organizations into a union as a result of a series of strikes in 1965, when the mostly Filipino farmworkers of the AWOC in Delano, California initiated a grape strike, and the NFWA went on strike in support.  As a result of the commonality in goals and methods, the NFWA and the AWOC formed the United Farm Workers Organizing Committee on August 22, 1966.

Farm Workers Union of Central Sweden: Farm Workers Union of Central Sweden (Swedish: "Mellersta Sverges lantarbetareförbund" ) was a trade union for agricultural workers in Sweden.  The organization was active between 1906 and 1908.  Carl Albert Svedberg was the chairman of the Farm Workers Union of Central Sweden.  As of September 1907 the union had around one hundred local sections.  The membership of the Farm Workers Union of Central Sweden was to a large extent concentrated to certain large agricultural estates.  The key areas of activities of the union were located around Mälaren.  The organization also established its presence in Västergötland, Östergötland, Dalarna and Gästrikland.

U.S. Route 99 in California: U.S. Route 99 (US 99) was the main north–south United States Numbered Highway on the West Coast of the United States until 1964, running from Calexico, California, on the US–Mexico border to Blaine, Washington, on the U.S.-Canada border.  Known also as the "Golden State Highway" and "The Main Street of California", US 99 was an important route in California throughout much of the 1930s as a route for Dust Bowl immigrant farm workers to traverse the state.  It was assigned in 1926 and existed until it was replaced for the most part by Interstate 5.  A large section in the Central Valley is now State Route 99.

Dust Bowl: The Dust Bowl, also known as the Dirty Thirties, was a period of severe dust storms that greatly damaged the ecology and agriculture of the American and Canadian prairies during the 1930s; severe drought and a failure to apply dryland farming methods to prevent wind erosion (the Aeolian processes) caused the phenomenon.  The drought came in three waves, 1934, 1936, and 1939–1940, but some regions of the high plains experienced drought conditions for as many as eight years.  With insufficient understanding of the ecology of the plains, farmers had conducted extensive deep plowing of the virgin topsoil of the Great Plains during the previous decade; this had displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds.  The rapid mechanization of farm equipment, especially small gasoline tractors, and widespread use of the combine harvester contributed to farmers' decisions to convert arid grassland (much of which received no more than 10 inches (250 mm) of precipitation per year) to cultivated cropland.

Philip Vera Cruz: Philip Vera Cruz (December 25, 1904 – June 12, 1994) was a Filipino American labor leader, farmworker, and leader in the Asian American movement.  He was a co-founder of the Agricultural Workers Organizing Committee, which later merged with the National Farm Workers Association to become the United Farm Workers.  As the union's long-time vice president, he worked to improve the working conditions for migrant workers.

Nagi Daifullah: Nagi Daifullah (1949 - August, 1973; Arabic: ناجي ضيف الله ) was a Yemeni migrant to the United States and union organizer with the United Farm Workers.  He was a strike captain during the 1973 grape farmers' strike organized by Cesar Chavez.  Daifullah spoke Arabic, English, and Spanish, and was integral in not only organizing the Yemeni community but also transcending ethnic and linguistic barriers between workers.  One report by the United Farm Workers Organizing Committee comments on Daifullah's importance as a strike leader:

Cesar Chavez: Cesar Chavez (born César Estrada Chávez, ] ; March 31, 1927 – April 23, 1993) was an American labor leader and civil rights activist who, with Dolores Huerta, co-founded the National Farm Workers Association (later the United Farm Workers union, UFW) in 1962.  Originally a Mexican American farm worker, Chavez became the best known Latino American civil rights activist, and was strongly promoted by the American labor movement, which was eager to enroll Hispanic members.  His public-relations approach to unionism and aggressive but nonviolent tactics made the farm workers' struggle a moral cause with nationwide support.  By the late 1970s, his tactics had forced growers to recognize the UFW as the bargaining agent for 50,000 field workers in California and Florida.  However, by the mid-1980s membership in the UFW had dwindled to around 15,000.

U.S. Route 99: U.S. Route 99 (US 99) was a main north–south United States Numbered Highway on the West Coast of the United States until 1964, running from Calexico, California, on the US–Mexico border to Blaine, Washington, on the U.S.-Canada border.  It was assigned in 1926 and existed until it was replaced for the most part by Interstate 5.  Known also as the "Golden State Highway" and "The Main Street of California", US 99 was important throughout much of the 1930s as a route for Dust Bowl immigrant farm workers to traverse the state.  Large portions are now California's State Route 99 (SR 99), Oregon Route 99, 99W, 99E and Washington's SR 99.  The highway connected to British Columbia Highway 99 at the Canada–US border.

Obreros Unidos: Obreros Unidos (1966–1971) was an independent agricultural labor union founded in Wisconsin in 1966 by Mexican American civil rights activists Jesus Salas, Francisco Rodriguez and many more, originally Texas-based farm workers from the small town of Crystal City.  The union took root after a march from Wautoma, Wisconsin, to Madison, Wisconsin that state's capitol to protest the working conditions of the thousands of annual Mexican-American migrant workers who traveled from Texas to Wisconsin each year.  This protest march was inspired by the similar march of César Chávez' United Farm Workers (UFW) in California earlier that spring, and the Texas Farmworker march on Austin, Texas of 1966.  Obreros Unidos engaged in its first labor action by seeking to organize migrant potato harvest and processing workers in the town of Almond, WI, and received support from the AFL-CIO, Cesar Chavez, and other labor unions.  The name means "united workers" in Spanish.

Richard Chavez: Richard Estrada Chavez (November 12, 1929 – July 27, 2011) was an American labor leader, organizer and activist.  Chavez was the younger brother of labor leader César Chávez, who co-founded the National Farm Workers Association, now known as the United Farm Workers (UFW).  Richard Chavez is credited with building the United Farm Workers into a major California agricultural and political organization.

Supporting paragraphs: U.S. Route 99 Dust Bowl
Answer: Calexico, California, on the US–Mexico border to Blaine, Washington, on the U.S.-Canada border