[GK] When the Districts in Tamil Nadu came into force?

S. No	District	Date of Formation
1	Chennai	01-11-1956
2	Coimbatore	01-11-1956
3	Madurai	01-11-1956
4	Kanyakumari	01-11-1956
5	Ramanathapuram	01-11-1956
6	Salem	01-11-1956
7	Thanjavur	01-11-1956
8	Triuchirappalli	01-11-1956
9	Thirunelveli	01-11-1956
10	The Nilgiris	01-11-1956
11	Dharmapuri	02-10-1965
12	Pudukottai	14-01-1974
13	Erode	31-08-1979
14	Sivagangai	15-03-1985
15	Virudhunagar	15-03-1985
16	Dindigul	15-09-1985
17	Tuticorin	20-10-1986
18	Thiruvannamalai	30-09-1989
19	Vellore	30-09-1989
20	Nagapattinam	18-10-1991
21	Thiruvarur	18-10-1991
22	Cuddalore	30-09-1993
23	Viluppuram	30-09-1993
24	Karur	30-09-1995
25	Perambalur	30-09-1995
26	Theni	25-07-1996
27	Namakkal	01-01-1997
28	Kancheepuram	01-07-1997
29	Thiruvallur	01-07-1997
30	Krishnagiri	09-02-2004
31	Ariyalur	23-11-2007
32	Tiruppur	22-02-2009
33	Tenkasi	22-11-2019
34	Kallakurichi	26-11-2019
35	Ranipet	28-11-2019
36	Tirupattur	28-11-2019
37	Chengalpet	29-11-2019
38	Mayiladuthurai*	-----------------------

* à Mayiladuthari became 38th district of Tamil Nadu, when the government notified it in a gazette on April 07, 2020. Mayiladuthari to be bifurcated from Nagapattinam Dt. 

With the announcement of Mayiladuthurai as a separate district, six new-districts have been created under the regime of the Mr. Edappadi K. Palaniswami-led AIADMK government in the past one year.

Tamil Nadu Districts - Based on their Area 
Tamil Nadu Districts - Based on their Population

[GK] Tamil Nadu Districts [Population wise]

S. No	District	Population
1	Chennai	4646732
2	Thiruvallur	3728104
3	Salem	3482056
4	Coimbatore	3458045
5	Madurai	3038252
6	Triuchirappalli	2722290
7	Cuddalore	2605914
8	Chengalpet	2556244
9	Tiruppur	2479052
10	Thiruvannamalai	2464875
11	Thanjavur	2405890
12	Erode	2251744
13	Dindigul	2159775
14	Viluppuram	2093003
15	Virudhunagar	1942288
16	Krishnagiri	1883731
17	Kanyakumari	1870374
18	Tuticorin	1750176
19	Namakkal	1726601
20	Thirunelveli	1665253
21	Pudukottai	1618345
22	Nagapattinam	1616450
23	Vellore	1614242
24	Dharmapuri	1506843
25	Tenkasi	1407627
26	Kallakurichi	1370281
27	Ramanathapuram	1353445
28	Sivagangai	1339101
29	Thiruvarur	1264277
30	Theni	1245899
31	Ranipet	1210277
32	Kancheepuram	1166401
33	Tirupattur	1111812
34	Karur	1064493
35	Ariyalur	754894
36	The Nilgiris	735394
37	Perambalur	565223
38	Mayiladuthurai	----------
	Total Population	71875403
Source: as per government website (tn.gov.in)

* à Mayiladuthari became 38th district of Tamil Naduw hen the government notified it in a gazette on April 07, 2020. Mayiladuthari to be bifurcated from Nagapattinam Dt. 

With the announcement of Mayiladuthurai as a separate district, six new-districts have been created under the regime of the Mr. Edappadi K. Palaniswami-led AIADMK government in the past one year.