Struggle with love-hate relationship with immigrants,

Oddly for a nation made up mostly of immigrants, the United States has always had a problem with immigration. Long before President Donald Trump called for building a wall on the U.S.-Mexico border, generations of Americans have advocated limiting immigration. In the 1800s, the Irish were a favorite target, and newspaper want ads commonly included the phrase, "No Irish need apply." Also in the 19th century, anti-immigration sentiment was codified in federal laws that singled out Asians. Subsequent federal laws targeted Italians and other Southern Europeans.

Scholars have identified three waves of immigration: the first era, the second era and the current era. As the U.S. once again debates who should be let into the country, perhaps it's time to review major immigration laws passed from 1870 to the present day. Some tried to bring order to the immigration process. Others aimed to keep out those perceived as un-American.

FIRST ERA, 1840s TO 1880s

Poor and unskilled immigrants from Northern Europe and Asia poured into the United States in the mid-1800s. Most of the European immigrants were German and Irish, and under the law they were considered "free white persons" able to achieve citizenship.

Citizenship wasn't an option for the growing numbers of Chinese and Asian immigrants settling on the West Coast. These immigrants were constant targets of abuse, and Chinese women were largely assumed to be prostitutes.

The growing animus against Asians across the country led to discriminatory laws that would remain on the books for decades.

Laws passed during this era 1870: Naturalization Act

Allowed African immigrants and those of African descent to become U.S. citizens. Other nonwhites remained unable to obtain citizenship.

1875: Asian Exclusion Act

Established federal regulation of immigration.

Prohibited bringing Asians into the U.S. without their consent and supplying Asians for labor.

1882: Chinese Exclusion Act

The first law to limit immigration based on a specific ethnicity.

Prohibited "skilled and unskilled laborers and Chinese employed in mining" from coming to the U.S. for 10 years. Prohibited state and federal courts from granting citizenship to Chinese immigrants (those courts had such power at the time). The act was extended repeatedly over the decades but repealed in 1943 during World War II to maintain a military alliance with China.

SECOND ERA, 1890S TO 1920S

During the next wave of immigration, laws continued to target Asians, but also tried to discourage immigration from Southern and Eastern Europe.

The poor, the sick and those espousing certain political beliefs were barred from entry under other new laws. Laws discouraging immigration from Southern Europe—mainly from Italy—reflected widespread anti-Catholic sentiment.

Laws passed during this era 1891: Immigration Act

Established a federal Bureau of Immigration and allowed deportation of immigrants in the country illegally or excluded by previous laws.

Also prohibited bringing people to the U.S. unlawfully and banned a wide variety of individuals, including polygamists, paupers, "idiots" and "persons suffering from a loathsome or a dangerous contagious disease."

1892: Geary Act

Extended the Chinese Exclusion Act for 10 more years.

Required people of Chinese ancestry, whether immigrants or U.S.-born, to obtain identification papers and carry them at all times or face prison or deportation.

1921: Emergency Quota Act

Created the first numerical quotas for immigration based on nationality to discourage immigration from Eastern and Southern Europe, whose people were widely considered un-American because of their political and religious affiliations. 1924: Johnson-Reed Act

Established a quota system based on country of origin. Northern European immigrants had better chances at being allowed to stay than any other groups, and Japanese immigrants were prohibited.

Limited annual immigration to 165,000, scaling back earlier caps.

CURRENT ERA, 1960S TO PRESENT

The immigration system in place today began to take shape with the 1965 HartCeller Act, which eliminated the quota system based on national origin.

Reflecting larger, global conditions, later laws addressed refugees, border security or illegal immigration. Executive actions by President Barack Obama prompted praise and criticism.

Laws passed during this era

1965: Immigration and Nationality Act (Hart-Celler Act)

Dramatically changed immigration policy by eliminating the quota system based on national origin. The law placed an emphasis on admitting skilled workers and family reunification. There were no limits on the number of immediate family members of U.S. citizens admitted per year.

1986: Immigration Reform and Control

Act (Simpson-Mazzoli Act)

One of the most sweeping immigration laws in U.S. history, allowing permanent residency for workers who had lived in the U.S. illegally since 1982 or worked in certain agricultural jobs. The law gave almost 3 million people legal status, denounced by many as "amnesty."

Called for stricter border enforcement and sanctions on employers hiring people in the country illegally (critics say the sanctions lacked teeth and have been applied unevenly). Protected children of those legalized by the act from deportation. Created a visa for temporary, seasonal agricultural workers, and the annual immigration ceiling rose to 540,000.

2002: Homeland Security Act

Created the Department of Homeland Security following the Sept. 11, 2001, terrorist attacks.

Created an electronic data system to maintain information on the admission of immigrants and on possible grounds for removal from the country.

2012: Deferred Action for Childhood

Arrivals (DACA)

An executive action, not a law, that shielded more than 752,000 young adults from deportation.

Granted two-year work permits to certain people ages 15 to 30 who were brought to the U.S. illegally as children.

2014: Deferred Action for Parents of Americans and Lawful Permanent Residents (DAPA)

An executive action, not a law, that sought to remove the threat of deportation for more than 4 million immigrant parents of U.S. citizens or lawful permanent residents.

Implementation of DAPA was initially blocked by a federal judge. In June the Trump administration announced it was ending the program.

IMMIGRATION IN THE TRUMP ERA

President Trump, who made cracking down on illegal immigration a centerpiece of his campaign, has stepped up deportation efforts and continues to call for a wall on the U.S.-Mexico border.

Aug. 2: Reforming American Immigration for Strong Employment (RAISE) bill

Trump endorsed this measure that, in a departure from the 1965 Hart-Celler Act, would create an immigration system based on merit and skills instead of family connections. It's estimated the measure would cut legal immigration by half.