More of Facebook’s growth appeared to be coming from abroad than in the US over the course of November, according to our latest review of reports from third-party web measurement firms.

In fact, compared to the past few months, up through our last look, at October data, it’s basically flat in the US. Perhaps Facebook is starting to max out its market penetration in this country? Still, from the data available, that doesn’t appear to be the case around the world.

Notes before we get started: The firms report data at varying points during and after each month, and they also use varying methodologies. We do our best to compare them, but considering the discrepancies, take each number with a grain of salt.

Compete

Following a long slow rise, Facebook’s US traffic tapered off slightly from 133.5 million monthly unique visitors in October down to 132.7 million in November. That difference could just be due to the fact that the latter month is shorter — still, growth appears to be flat.

ComScore

The same story continues with the next firm, at least in the US. Facebook grew from 151.1 million in October to 151.7 in November, which is not much compared to past months.

Worldwide, however, Facebook grew a healthy 14 million or so users over November, reaching 647.5 million by the end of the month.

Google Ad Planner

Worldwide, Google’s DoubleClick measurement service lists the same number it did a month ago — 590 million monthly uniques around the world. The daily active user count appears to have hit nearly 300 million by the beginning of December (but has fallen back slightly since then).

Quantcast

In what appears to have been an unannounced recalculation, the firm is now showing Facebook 129 million monthly unique visitors. That’s the most it has ever tracked, according to the site today. But when we looked last month, Quantcast was showing Facebook had plateaued at 137 million monthly uniques. Apparently there was some sort of methodology change.

Conclusion

All in all, Facebook’s November US traffic appears to be flat, while comScore — which provides the clearest month-to-month worldwide data — is showing monthly gains as normal.

For reference, we separately track the data that Facebook self-reports in its advertising tool. We recorded it bringing in 145.3 million monthly active users, up 2.25 million from the previous month. Worldwide, we tracked Facebook gaining 22 million users over the course of the month to reach 573 million. (You can view a full set of demographic data, along with our analysis, in our Inside Facebook Gold report.)

Another important point here is what’s happening with Twitter — most firms show it more or less flat in the US, but it continues to zoom up around the world.

Each data source has typically showed a halting upward climb for Facebook, especially when one zooms in to look at the US or other specific countries. The more important thing is to watch for longer-term trends. And overall, that continues to be Facebook gaining more users. Stay tuned, as we’ll take a year-end look once December data is out.