Top Megacities in 2015

There is wide discrepancy in the sources for population, so I made a chart.  There are 31 megacities in the world today if London is included and Shenzhen is excluded (part of Pearl River Delta)

	Most Populous Urban Areas in the World
Rank	City	Economist [1]	Worldbank [2]	Demographia [3]	CityPopulation .de [4]	Wikipedia [5]
1	Pearl River Delta		41.8			41.8
NA	Guangzhou-Foshan			20.6	34.3
NA	Guanghzou, China	9.6
NA	Foshan, China	6.7
NA	Dongguan, China	7.1		8.4
NA	Shenzhen, China	10.2		12.1	12.3
	Total Pearl River Delta	33.6	41.8	41.1	46.6	41.8
2	Tokyo, Japan	36.8	31.8	37.8	39.4	37.2
3	Jakarta, Indonesia	9.6	23.4	30.5	27.4	26.7
4	Seoul, South Korea	9.8	15.9	23.5	24.2	25.4
5	Delhi, India	21.9		25.0	25.7	22.8
6	Shanghai, China [6]	20.0	24.2	23.4	30.2	21.8
7	Manila, Philippines	11.9	16.5	24.1	22.8	21.2
8	Karachi, Pakistan	14.1		22.1	23.6	20.9
9	New York, US	18.4		20.6	21.9	20.7
10	Sao Paulo, Brazil	19.7		20.4	21.6	20.6
11	Mexico City, Mexico	20.1		20.1	22.4	20.0
12	Beijing, China	16.2	16.7	21.0	20.3	18.2
13	Mumbai, India	19.4		17.7	22.8	17.3
14	Osaka, Japan	19.5	12.2	17.4	17.8	17.2
15	Moscow, Russia	10.5		16.2	16.8	15.8
16	Cairo, Egypt	16.9		15.6	16.5	15.1
17	Los Angeles, US	12.2		15.1	17.4	15.1
18	Tehran, Iran	8.1		13.5	13.5	14.7
19	Kolkata, India	14.3		14.7	15.8	14.6
20	Bangkok, Thailand	8.2	9.6	15.0	15.1	14.5
21	Dhaka, Bangladesh	14.7		15.7	17.0	14.4
22	London, UK	9.7		10.2	14.1	9.6
23	Buenos Aires, Argentina	14.2		14.1	15.8	13.8
24	Istanbul, Turkey	12.7		13.3	14.2	12.9
25	Lagos, Nigeria	10.8		13.1	13.7	12.1
26	Rio de Janeiro, Brazil	12.4		11.7	12.6	11.6
27	Paris, France	10.5		10.9	11.2	10.9
28	Tianjin, China	9.5	8.8	10.9	11.1	9.3
29	Nagoya, Japan	9.2		10.2	10.4	10.2
30	Kinshasa, Dem Rep Congo	9.4		11.6	10.3	9.4
31	Bangalore, India	8.3		9.8	10.1	9.0
NA	Bogota, Colombia	8.5		9.0	9.3	9.9
NA	Lima, Peru	9.0		10.8	9.9	9.4
NA	Chennai, India	8.5		9.7	9.8	9.2
NA	Chicago, IL	8.6		9.2	9.8	9.1
NA	Chengdu, China	6.2	8.3	10.4	9.0	8.4
NA	Lahore, Pakistan	7.5		10.1	9.8	8.0
NA	Chongqing, China	11.2	5.0	7.2	6.9	6.6
NA	Suzhou, Jiangsu, China	4.0		5.2		4.4

Notes:
[1] http://www.economist.com/node/21642053?fsrc=scn/fb/wl/bl/dc/dailychart
[2] http://www.worldbank.org/content/dam/Worldbank/Publications/Urban%20Development/EAP_Urban_Expansion_full_report_web.pdf
[3] http://demographia.com/db-worldua.pdf
[4] http://citypopulation.de/world/Agglomerations.html
[5] http://en.wikipedia.org/wiki/List_of_urban_areas_by_population
[6] Does Shanghai include Suzhou? Yes in sources 2 and 4, no in the others.