Exploring America’s past and future metaphorically through dendrochronology

The United States frequently dons the moniker “the melting pot” a name that is deeply rooted in our history of immigration. As of late, there has been a resurgence in dialogue about the impact of immigration on our economy. This is a cyclical occurrence. This history and data have been visualized many times over. However, the most exciting approach to date can be found in the KantarInformation is Beautiful award-winning “dendrographic” produced by Pedro Cruz, John Wihbey, and their colleagues from Northeastern University.
Recently, I had the opportunity to discuss how the team used their metaphorical approach to deliver a visualization that portrays the country as a living organism while highlighting its diversity with Pedro Cruz, Assistant Professor at Northeastern University’s College of Arts, Media and Design (CAMD).
Cruz along with CAMD colleagues John Wihbey, Avni Ghael, and Felipe Shibuya created a simulated dendrochronology* of U.S. Immigration from the years 1790–2016 imagining each decade as a ring in a growing tree trunk. This visualization depicts the waves of immigrants entering over the decades and begins to show the growing diversity of the United States over time.
Dendrochronology is the technique of studying climatic and ecological change over time via tree rings. The bigger, older and mightier the tree, the more rings it has and the more data can be extracted.
The United States is a Mighty Redwood
When creating the dendrographic, Prof Cruz and the team wanted to illustrate our connection to nature. Each wave of immigration that has come to our shores over the decades has strengthened us. The byproduct is a mighty redwood. Each ring represents a decade of growth versus a year in regular trees. The cells that make up the rings represent 100 immigrants. An algorithm disperses the cells in a concentric pattern creating a colorful mosaic that is based on the origins of the immigrants. The color coding represents the origin of the immigrants and the positioning is relative to the geographic regions in which they settled. The visualization is also positioned to reflect the geographic regions of the United States. For example, we see a heavy flow of Asian immigrants settling to the West, Latin Americans settling in the South, and European immigrants settling along the East.
The dendrographic represents organic tree growth as a flow of immigrants contracts during times of more restrictive immigration policies. By contrast, economic recession and expansion during greater opportunities and less restrictive immigration policies.


The tree grows more in directions where immigration is coming from. Starting from the center or “heartwood” we have an immigration flow that shows the influx of early European immigrants. As time progresses, we see Asian immigrants settling in the Western U.S., Canadians settling in the Great Plains and Midwest, and Latin Americans and Caribbeans immigrating primarily in the South. As we approach the outer fringes, the bark, we see sprinkles of color beginning to diversify the Eastern half of the country.
The width of the rings is quite telling! The earlier rings show thickness along the Eastern U.S. from European immigrants while the West creates narrow bands earlier on as Asian and Latin American immigrants first enter the country. As time progresses, the Asian and Latin American sections of the bands widen as the predominantly European sections along the East narrow. Through the visualization, I explored seasonality and conditions that contributed to the shifts illustrated.
The Chinese Exclusion Act of 1882
Around 1850, A large wave of Chinese immigrants entered the United States to join the Gold Rush. This migration caused an uproar from white miners as they blamed the Chinese for declining wages and economic downturn. Congress responded to this sentiment by bypassing the Exclusion Act, the first restrictive immigration law. This act suspended Chinese immigration for ten years and declared Chinese immigrants ineligible for naturalization. The result is expressed in the dendrographic with narrowing sections of Asian immigration in this period. Simultaneously, we see trickles of Canadian and Latin American immigrants forming. In contrast, we see that European immigration to the East is going strong through the 1850s.


San Francisco Plague of 1900–1904
At the turn of the century, the world was hit with the Bubonic Plague pandemic. This was the first plague outbreak to hit U.S. shores. How would this pandemic impact immigration flow? The pandemic initially impacted San Francisco’s Chinatown area. With the Chinese Exclusion Act still in place, this plague was most likely a backdrop in terms of impact on Asian immigration. This pandemic however did highlight the racial discrimination against Chinese Americans as the State of California made attempts to keep the plague quiet in fear of it damaging their economy.
Spanish Flu Pandemic of 1918
The Spanish Flu, the deadliest pandemic in history, infected 500 million people, a third of the world population, and killed 20 to 50 million worldwide; 675,000 Americans included. Referring back to the dendrographic, this pandemic coincided with a major wave of immigration to the United States with more than 23.5 million newcomers arriving between 1880 and the 1920s. The latest wave of European immigrants was from the Southern and Eastern regions like Italy and Poland
Concurrent with the Spanish Flu was World War I, collectively, these events slowed immigration dramatically. While this pandemic was widespread and affected many people of various socioeconomic backgrounds, prejudice towards newcomers was prevalent. Italian immigrants had been blamed for the spread of polio and were also blamed for the pandemic. Furthermore, German immigrants were accused of spreading the disease as a war tactic. Medicalized prejudice became the foundation for the arguments of immigration restrictionists. We would begin to see the impact of these sentiments several years later.

Immigration Act of 1924
The Immigration Act of 1924 limited the number of immigrants allowed entry into the United States through a national origins quota. The quota provided immigration visas to two percent of the total number of people of each nationality in the United States as of the 1890 census. This methodology completely excluded immigrants from Asia. One of the basic purposes of this act was to satisfy immigration restrictionists and promote what was termed as U.S. homogeneity.
The dendrographic illustrates the narrowing of the Asian immigration due to the combined impact of The Chinese Exclusion Act and the Immigration Act of 1924-which limited the number of Japanese immigrants. Filipino immigrants continued to immigrate to America as the Philippines was a U.S. colony at the time. As for European immigrants, the quota system limited the number of Southern and Eastern Europeans given that the majority of Europeans in 1890 were from the North i.e. England. In the 1930’s a significant drop in European immigration can be attributed to distraction caused by the Great Depression, followed by World War II.
Immigration and Naturalization Act of 1965
Also known as the Hart-Celler Act, this legislation established a new immigration policy replacing the quota system for reuniting immigrant families and attracting skilled laborers to the U.S. Motivated by the civil rights movement’s focus on equal treatment regardless of race or nationality, this act greatly changed the demographic makeup of the American population. Immigrants began entering from Asian, African, and Latin American countries; in addition to Greeks, Poles, Portuguese, and Italians.
Looking at the dendrographic, we can see an explosion of Asian and Latin American immigrants after the bill’s passage. In addition, to Civil Rights, the 1960s and 1970s were painted by the Cold War. Immigrants were fleeing Vietnam, Cuba, Eastern Europe in the hopes of a better life. The next three decades after the passage of the Immigration and Naturalization Act of 1965 would bring more than 18 million legal immigrants into the United States.
By the end of the 20th century, the landscape of the American population had drastically changed. The density of the European migration, approximately 50% through the 1950s had thinned to only 15% in the 1990s. Whereas the pendulum shift allowed for Asian growth, this population grew from a meager 5% in the 1950s to 31% in the 1990s. During this same period, we can clearly see the wave of Latin American and African immigrants as well.
Asians Lead 21st Century Immigration Flow
History, like the rings on the tree and the dendrographic is cyclical. In the absence of facts and education, it inevitably repeats itself. Educating the masses through visualization was front of mind for Cruz. Currently, we are embroiled in Immigration hearsay. The sentiment that is circulating suggests that we are overrun by less-skilled immigrants from Mexico and Latin America. In reviewing the facts, we note that Latin American immigration peaked in the decades between 1965 and 2000 with 4.3 million immigrants. Over the last two decades, however, it has narrowed and the growing wave of immigrants today is Asian.
Clearly visible in the outer two rings of the visualization — a narrowing wave of Latin American immigrants with a growing wave of Asian immigrants. According to demographer and senior fellow at the Brookings Institution, William Frey, Asian immigrants now surpass Latin immigrants as the majority foreign-born residents that have arrived since 2010. In his blog post, he states that 41 percent of those who have arrived since 2010 were born in Asia compared with 38.9 percent from Latin America. He further goes on to write that these immigrants are more prone to obtaining a college education.

The United States is a Nation of Immigrants
Through Pedro and the team’s dendrographic we are able to visualize U.S. immigration, the impacts of law, economic conditions, and world events on the shape of our “tree.” From the 20th century waves of European immigrants flowing in as the tide of Asian immigrants ebbed due to restricted immigration laws.
The 20th century saw waves of European immigrants flowing in as the growth of Asian immigrants diminished due to restrictive immigration laws. The U.S. would experience pandemics, world wars, economic downturns, and a civil rights movement before the immigration floodgates opened back up with the Immigration and Naturalization Act of 1965. Lifting national quotas led to a larger number of immigrants from all parts of the world particularly from Latin America through the 1990s. The 21st century has brought a new wave of immigrants. The latest influx of Asian immigrants are more educated and graduating from college at a rate that outpaces native-born Americans.
The Impact of Covid-19
The world is currently experiencing an epic pandemic. As of May 10, 2020, Covid-19 has infected more than 4.2 million people and killed 285,000 people worldwide according to John Hopkins University. In the United States more than 1.3 million cases have been recorded and 81,000 deaths.
This global crisis has caused panic and an economic downturn as well as a race for a vaccine. How will this pandemic affect U.S. immigration? So far the U.S. has extended non-essential travel restrictions with Canada and Mexico. Visa requirements have been temporarily amended for foreign workers who are relied on by U.S. agricultural employers. Immigration hearings have been postponed indefinitely. These are only some of the dynamics forming as this drama develops.
This virus is believed to have started in a sprawling city named Wuhan, China. What are the far-reaching implications if China is held responsible for this pandemic? As of now, that has not been addressed but based on past history we have observed the ripple effect that pandemics and economic downturns have had on immigration policies.
Acknowledging the Past
Giving a nod to Asian Pacific American Heritage Month, check out this TIMEarticle on how Jeanie Jew, a former Capitol Hill staffer, fought to make this celebration happen. She is described as “turning a personal tragedy in her family history into a positive force” at the 1992 congressional hearing that introduced the legislation to designate May as the commemorative month. Jew’s great-grandfather was one of the 20,000 Chinese immigrants who’d come to America in the 1800s looking for a better life. He and his peers worked on the Transcontinental Railroad but would later have their contributions marginalized due to anti-Chinese sentiment. The Transcontinental Railroad opened up numerous economic opportunities for the United States and extended travel immensely. It is this and many other contributions that highlight how diversity adds to the strength and progress of this great nation.
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