The 6-foot-1 Parke is strong in the air, something the Union need.
"He is one of the top center backs in the league," Union team manager John Hackworth said. "His character and experiences as both a person and a player will definitely be welcomed in our locker room."
Parke, who earned $189,000 last season, was acquired for allocation money and a first-round pick in the 2013 MLS supplemental draft.
Union CEO and operating partner Nick Sakiewicz said a simpler term for allocation money is "cash."
Either way, that cash went a long way toward bringing in two starters for next year.
Le Toux collected 25 goals and 20 assists in the Union's first two MLS seasons before being traded to Vancouver; he was subsequently dealt to New York. The Union acquired him from the Red Bulls for forward Josue Martinez and allocation money.
Terms of Le Toux's contract were not released, but a source confirmed that it was a multiyear deal. Le Toux earned $169,000 last year, according to MLS Players Union figures.
Le Toux, the Union's first all-star in their inaugural season in 2010 and a fan favorite, left no doubt that he would like to stay for several seasons.
"I would like to stay here forever," he said during a news conference at PPL Park.
Le Toux played midfield for Vancouver and New York, but Hackworth said he would be better off playing up top.
"It's the position he has been the most successful at and the position we needed," said Hackworth, whose 10-18-6 team scored just 37 goals, which was 15th in the 19-team MLS.
Le Toux never wanted to leave in the first place, but he got into a dispute with former team manager Peter Nowak, who was replaced by his assistant Hackworth after 11 games last season. Sakiewicz mentioned how pleasant it is working with Hackworth on transactions.
"John's style of picking players on the roster is very collaborative," Sackiewicz said. "It is very refreshing to me as an owner and the rest of our investment group because we were kind of in the dark on a lot of this stuff."
Contact Marc Narducci at email@example.com, or follow on Twitter @sjnard.