When Boeing Co. announced in 2009 it was bringing its 787 Dreamliner assembly line to North Charleston, it promised at least 3,800 jobs within seven years in a $750 million plant.

It far surpassed that goal, with more than 6,600 workers now at the airplane-making operation at Charleston International and an interiors fabrication plant in Palmetto Commerce Park about 10 miles from the main airport campus.

Last year, it announced a second expansion that would bring another 2,000 jobs by 2020 through another $1 billion investment after the state offered $120 million in incentives.

How many of those jobs and how much investment have been committed already?

It's hard to say, and it's hard to pin down why there is so much secrecy. Boeing South Carolina won't release the actual number of positions or investments made since last April, and the S.C. Commerce Department, to which the number of jobs and investment must be reported, says, through spokeswoman Allison Skipper, it's under no obligation to keep up with them until 2020, when a final report will be made by Boeing.

Based on public announcements last year of new positions tied to the $1 billion investment, several hundred of the 2,000 promised jobs are on the way. A lot more are expected.

First, when Chicago-based Boeing last fall announced its new jet propulsion factory being built at Palmetto Commerce to produce engine inlet components for the 737 MAX single-aisle jet, it didn't announce the number of jobs or the dollar investment, but it said the factory would initially have parking for 300 spaces. It's expected to open by the end of the year and could triple in size, depending on production.

So for now, it's probably safe to say Boeing will generate 300 or fewer jobs at the site in its startup phase.

Second, the company announced some of the engineering design work for the 777X, which will be built in Washington state, will come to North Charleston. Again, it didn't say how many jobs or what the capital investment would be.

Third, in December Boeing announced it would bring 300 to 400 jobs through a new manufacturing research center. It didn't announce the dollar investment, but said it would, in the short term, lease a facility to house the workers.

Based on those three announcements, a conservative guess would be at least 600 of the 2,000 workers tied to the $120 million inducement.

If Boeing follows its first round of investment, the final number will far surpass the 2,000 workers promised. All signs point in that direction.

The company recently leased 468 acres of additional land near the airport for future expansion. It assembles the 787-8, the smallest of the twin-aisle jets in the series in North Charleston. Starting this fall, it will begin producing the 787-9, a stretch version of the twin-aisle passenger jet. A decision on the assembly site for the 787-10, the biggest version of the plane, will be made by March.

A wetlands mitigation document for the recently leased wooded acreage shows the flight line increasing to 16 aircraft parking stalls from seven and the main assembly building growing by about two-thirds. The total square footage of enclosed space across the entire campus will almost triple starting in 2016.

Boeing will also ramp up production of the 787 in North Charleston and Everett, Wash., to 12 jets a month starting in 2016 and 14 a month starting in 2019.

All of these measures taken together mean the company will mostly likely not only meet its goal of adding 2,000 more workers, but go way beyond it by 2020. Time will tell.

Reach Warren L. Wise at 937-5524 or twitter.com/warrenlancewise.