1.  Marriage Record:

2.  1900 Census Every-Name-Index/Images (online at Ancestry.com, Image #2 of 31):  33 West Monroe St., Little Falls (Ward 2), Herkimer Co., NY, Roll T623_1040 (Book 1), p. 72B, SN 1, SD 7, ED 53, enumerated 1 Jun 1900, official enumeration date 1 Jun 1900 (extracted by Diana Gale Matthiesen):¤•

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
		1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	19	20	22	23	24	25	27
*	33	17	19	Ecker John	Head	W	M	May 1858	42	M	19			NY	NY	NY			Electrician	0	Y	Y	Y	R	H
				[John's wife and children]
				Stroup Irving	Lodger	W	M	Nov 1864	35	M	1			NY	NY	NY			Dealer Tobacco & Cigars	0	Y	Y	Y
				______ Ida M	Lodger	W	F	Apr 1870	30	M	1	0	0	Eng	Eng	Eng	1875	25	Finisher Knitting Mill	0	Y	Y	Y
*West Monroe St

3.  1910 Census Index/Images (online at Ancestry.com, Image #2 of 22 — indexed "Erving"):  4 Elm Street, Utica City (Ward 7), Oneida Co., NY, Roll T624_1052 (Part 2), p. 163B, SN 1B, SD 11, ED 119, enumerated 15 Apr 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):¤•

1910:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
		1	2	3	4	5	6	7	8	9	10	11	12	13	14	17	18	19	20	21	22	23	24	26	28
*	4	26	30	Stroup Irving	Head	M	W	44	M2	6			New York	New York	New York	Eng	Helper	Plumber	W	N	0	Y	Y	R	H
				______ Mary	Wife	F	W	41	M1	6	0	0	England Eng	England Eng	England Eng	Eng	None					Y	Y
				Angus Mabel E	Lodger	F	W	32	S				New York	New York	Germany Ger	Eng	Teacher	Shorthand	W	N	0	Y	Y
*Elm Street

4.  1920 Census Index/Images (online at Ancestry.com, Image #40 of 50 — indexed "Straup"):  725 Park Avenue, Syracuse City (Ward 8), Onondaga Co., NY, Roll T625_1248 (Book 2), p. 61B, SN 20B, SD 16, ED 151, enumerated 14 Jan 1920, official enumeration date 1 Jan 1920 (extracted by Diana Gale Matthiesen):¤•

1920:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	9	10	11	12	13	14	15	17	18	19	20	21	22	23	24	25	26	27	28
*	725	231	413	Stroup Irving	Head	R	M	W	54	M				Y	Y	NY		NY		NY		Y	Assembler	Automobile Co	W
				______ Mary	Wife		F	W	48	M	1872	Na	1899	Y	Y	Eng	Eng	Eng	Eng	Eng	Eng	Y	None
				Sager Elizabeth	Lodger		F	W	50	S				Y	Y	NY		Ger	Ger	Ger	Ger		Tuber (sic)	Piano Co	W
*Park Avenue

5.  1930 Census Index/Images (online at Ancestry.com, Image #7 of 78):  446 Wilkinson Street, Syracuse City (Ward 2, Block 204), Onondaga Co., NY, Roll 1626 (Book 2), p. 20A, SN 4A, ED 34-18, SD 11, enumerated 9 Apr 1930, official enumeration date 1 Apr 1930 (extracted by Diana Gale Matthiesen):¤•

1930:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	30
*	446	105	177	Stroup Irving	Head	R	30	M	W	64	M	28	N	Y	NY	NY	NY				Y	Polisher	Auto factory	W	Y	N
				______ May	Wife			F	W	59	M	30	N	Y	Eng	Eng	Eng	Eng	1872	Na	Y	None
*Wilkinson Street

May/Mary says she married first at the age of 30, which jibes with her being the woman in the 1900 census who, at age 30, has just married.  What then becomes the error is the 1910 census, where it states their years married were 6 when they should be 11.  Also, if Irving married first at age 28, he married in 1891/2, which means he married someone prior to his wife in 1900.