Question: When did the maker of the Acura Legend, the employer of Katsuaki Watanabe, and Nissan open US assembly plants?

Knowledge 1: Katsuaki Watanabe
Watanabe, who earned a degree in economics from Tokyo's Keio University, joined Toyota upon graduating from that university in 1964. [SEP] Knowledge 2: Toyota
By the early 1960s, the US had begun placing stiff import tariffs on certain vehicles. The so - called ``chicken tax ''of 1964 placed a 25% tax on imported light trucks. In response to the tariff, Toyota, Nissan Motor Co. and Honda Motor Co. began building plants in the US by the early 1980s. [SEP] Knowledge 3: Acura Legend
The Acura Legend is a mid-size luxury/executive car manufactured by Honda. It was sold in the U.S., Canada, and parts of China under Honda's luxury brand, Acura, from 1985 to 1995, as both a sedan, which was classified as a full-size car, and a coupe, which was classified as a mid-size car (similar to how the Honda Accord is set up today). It was the first flagship sedan sold under the Acura nameplate, until being renamed in 1996 as the Acura 3.5RL. The 3.5RL was the North American version of the KA9 series Honda Legend.
Knowledge 1: Katsuaki Watanabe
Watanabe, who earned a degree in economics from Tokyo's Keio University, joined Toyota upon graduating from that university in 1964. [SEP] Knowledge 2: 1973 oil crisis
Some buyers lamented the small size of the first Japanese compacts, and both Toyota and Nissan (then known as Datsun) introduced larger cars such as the Toyota Corona Mark II, the Toyota Cressida, the Mazda 616 and Datsun 810, which added passenger space and amenities such as air conditioning, power steering, AM-FM radios, and even power windows and central locking without increasing the price of the vehicle. A decade after the 1973 oil crisis, Honda, Toyota and Nissan, affected by the 1981 voluntary export restraints, opened US assembly plants and established their luxury divisions (Acura, Lexus and Infiniti, respectively) to distinguish themselves from their mass-market brands. [SEP] Knowledge 3: Acura Legend
The Acura Legend is a mid-size luxury/executive car manufactured by Honda. It was sold in the U.S., Canada, and parts of China under Honda's luxury brand, Acura, from 1985 to 1995, as both a sedan, which was classified as a full-size car, and a coupe, which was classified as a mid-size car (similar to how the Honda Accord is set up today). It was the first flagship sedan sold under the Acura nameplate, until being renamed in 1996 as the Acura 3.5RL. The 3.5RL was the North American version of the KA9 series Honda Legend.
Knowledge 1: Katsuaki Watanabe
Watanabe, who earned a degree in economics from Tokyo's Keio University, joined Toyota upon graduating from that university in 1964. [SEP] Knowledge 2: Toyota
By the early 1960s, the US had begun placing stiff import tariffs on certain vehicles. The so - called ``chicken tax ''of 1964 placed a 25% tax on imported light trucks. In response to the tariff, Toyota, Nissan Motor Co. and Honda Motor Co. began building plants in the US by the early 1980s. [SEP] Knowledge 3: Acura RLX
The Acura RLX is a full-size luxury sedan manufactured by Honda and sold under their Acura division, released in 2013. Succeeding the Acura RL, the RLX offers two versions, a front-wheel drive base model equipped with Acura's Precision All-Wheel Steer (P-AWS) four-wheel steering system, and a hybrid variant featuring SH-AWD that serves as Acura's flagship. The JDM version, the Honda Legend, is only offered with the SH-AWD powertrain.

Answer: 1981