Ever since Xihang Liang and his wife immigrated to the United States from China 10 years ago, his biggest dream is to be reunited with his son, who he had to leave behind.

“When we first moved to the U.S., we missed him every day,” said Liang.

According to a recent report from the National Asian American Survey, there are currently 4.3 million people waiting abroad to come to the U.S. through family-based visas sponsored by family members who are U.S. citizens. On that long family immigrant waiting list, there are 1.8 million people from Asian countries.

Traditionally, families qualify for either the immediate relative or family preference immigrant visas. Immediate relative visas allow people who have a “close” family relationship with a United States citizen — spouses, unmarried children under the age of 21 or parents over the age of 21 — to be sponsored. There is no annual cap for immediate relative immigrant visas. However, family preference immigrant visas are for people who have a “distant” relationship with family who are U.S. citizens, including siblings, grandparents and children over the age of 21. People under this category have to wait for a period of time because there is an annual cap of 260,000 for the family preference immigrant visa. Because Liang’s son was married at the time when Liang petitioned for him to immigrant to the U.S., Liang’s son was subject to the family preference immigrant visa category, which meant a longer waiting period due to the high demand.

Erin Oshiro, a senior attorney at Asian American Justice Center, said the unbalanced supply and demand for family preference immigrant visas contributes to the backlog for family immigration visas that millions of people encounter.

“Our current immigration law puts numerical limits on some of the specific family categories,” said Erin Oshiro in an e-mail. “For example, brothers and sisters of U.S. citizens can only get 65,000 visas per year. Currently more than 2.4 million brothers and sisters are waiting for a chance at the 65,000 visas available annually.”

According to the Asian Pacific American Legal Center, Asian American Justice Center and New York Immigration Coalition, a married adult son or daughter from China must wait about 11 years before immigrating to the U.S.

Out of the seven countries with the worst family-based visa backlogs, five are in Asia.

“Family unification is a particular priority for the AAJC, because it impacts Asian Americans so disproportionately,” said Jessica Chia, staff attorney for Asian American Justice Center. “Because of the path exclusive policies, Asian Americans really rely on their families in the U.S.”

Liang waited 12 years to come to the U.S.. Now, he anticipates that one day he can bring his son.

“He sometimes asks me over the phone when he could come to the U.S.,” said Liang. “I told him that I didn’t know.”