March 29 was chosen as National Vietnam War Veterans Day because on March 29, 1973, Military Assistance Command, Vietnam (MACV) was disbanded and the last U.S. combat troops departed the Republic of Vietnam. 

On March 29, 2012, President Barack Obama proclaimed March 29, 2012, as Vietnam Veterans Day. The proclamation called "upon all Americans to observe this day with appropriate programs, ceremonies, and activities that commemorate the 50 year anniversary of the Vietnam War."

On December 26, 2016, the Vietnam Veterans Day Coalition of States Council presented a letter to President Elect Donald Trump and Congressional leadership outlining the history and timeline of cause to establish March 29 as Vietnam War Veterans Day and requesting that it be one of the first legislations passed and signed into law during the 115th Congress.

On March 28, 2017, President Trump signed the Vietnam War Veterans Recognition Act of 2017. This act officially recognizes March 29 as National Vietnam War Veterans Day. The Act also includes the day among those days on which the US flag should especially be displayed.
My Mayor’s Office chief of staff, Vernon Whitmore and I are both Vietnam veterans.

By the time I arrived in Vietnam, 1969-70, Army Engineers were preparing for “Vietnamization,” and substantially focused on building infrastructure. As an example, see Construction of Corduroy Road, MSR Zinc, Vietnam 1969. This video shows MSR (Military Service Road) Zinc from Ben Cat to Phuoc Vinh by the 34th Engineer Battalion, 159th Engineer Group, used an ancient technique called a "corduroy road" to overcome bottomless mud. This project took 17,880 tons of rock and 1,500 creosoted telephone poles for 500 meters of corduroy and 72,680 manhours. It was the first of its type built in Vietnam.

Of the 2.7 million Americans who served in Vietnam, approximately one-third are estimated to be living in 2022.

Figure 1 - Men of the HHC 159th Engineer Group, Long Binh 1969