Table 2: Performance comparisons. We bold the best-performing baseline result. The absence of baselines on the GLA and CA datasets indicates that the models incur out-of-memory issue even when we set batch size to 4 on an A6000 GPU with 48 GB memory. Param: the number of learnable parameters. K: kilo  $(10^{3})$ . M: million  $(10^{6})$ .
Data	Method	Param	Horizon 3	Horizon 6	Horizon 12	Average
MAE	RMSE	MAPE	MAE	RMSE	MAPE	MAE	RMSE	MAPE	MAE	RMSE	MAPE
SD	HL	-	33.61	50.97	20.77%	57.80	84.92	37.73%	101.74	140.14	76.84%	60.79	87.40	41.88%
LSTM	98K	19.03	30.53	11.81%	25.84	40.87	16.44%	37.63	59.07	25.45%	26.44	41.73	17.20%
DCRNN	373K	17.14	27.47	11.12%	20.99	33.29	13.95%	26.99	42.86	18.67%	21.03	33.37	14.13%
AGCRN	761K	15.71	27.85	11.48%	18.06	31.51	13.06%	21.86	39.44	16.52%	18.09	32.01	13.28%
STGCN	508K	17.45	29.99	12.42%	19.55	33.69	13.68%	23.21	41.23	16.32%	19.67	34.14	13.86%
GWNET	311K	15.24	25.13	9.86%	17.74	29.51	11.70%	21.56	36.82	15.13%	17.74	29.62	11.88%
ASTGCN	2.2M	19.56	31.33	12.18%	24.13	37.95	15.38%	30.96	49.17	21.98%	23.70	37.63	15.65%
STTN	114K	16.22	26.22	10.63%	18.76	30.98	12.80%	22.62	39.09	16.14%	18.69	31.11	12.82%
STGODE	729K	16.75	28.04	11.00%	19.71	33.56	13.16%	23.67	42.12	16.58%	19.55	33.57	13.22%
DSTAGNN	3.9M	18.13	28.96	11.38%	21.71	34.44	13.93%	27.51	43.95	19.34%	21.82	34.68	14.40%
DGCRN	243K	15.34	25.35	10.01%	18.05	30.06	11.90%	22.06	37.51	15.27%	18.02	30.09	12.07%
D²STGNN	406K	14.92	24.95	9.56%	17.52	29.24	11.36%	22.62	37.14	14.86%	17.85	29.51	11.54%
GBA	HL	-	32.57	48.42	22.78%	53.79	77.08	43.01%	92.64	126.22	92.85%	56.44	79.82	48.87%
LSTM	98K	20.38	33.34	15.47%	27.56	43.57	23.52%	39.03	60.59	37.48%	27.96	44.21	24.48%
DCRNN	373K	18.71	30.36	14.72%	23.06	36.16	20.45%	29.85	46.06	29.93%	23.13	36.35	20.84%
AGCRN	777K	18.31	30.24	14.27%	21.27	34.72	16.89%	24.85	40.18	20.80%	21.01	34.25	16.90%
STGCN	1.3M	21.05	34.51	16.42%	23.63	38.92	18.35%	26.87	44.45	21.92%	23.42	38.57	18.46%
GWNET	344K	17.85	29.12	13.92%	21.11	33.69	17.79%	25.58	40.19	23.48%	20.91	33.41	17.66%
ASTGCN	22.3M	21.46	33.86	17.24%	26.96	41.38	24.22%	34.29	52.44	32.53%	26.47	40.99	23.65%
STTN	218K	18.25	29.64	14.05%	21.06	33.87	17.03%	25.29	40.58	21.20%	20.97	33.78	16.84%
STGODE	788K	18.84	30.51	15.43%	22.04	35.61	18.42%	26.22	42.90	22.83%	21.79	35.37	18.26%
DSTAGNN	26.9M	19.73	31.39	15.42%	24.21	37.70	20.99%	30.12	46.40	28.16%	23.82	37.29	20.16%
DGCRN	374K	18.02	29.49	14.13%	21.08	34.03	16.94%	25.25	40.63	21.15%	20.91	33.83	16.88%
D²STGNN	446K	17.54	28.94	12.12%	20.92	33.92	14.89%	25.48	40.99	19.83%	20.71	33.65	15.04%
GLA	HL	-	33.66	50.91	19.16%	56.88	83.54	34.85%	98.45	137.52	71.14%	59.58	86.19	38.76%
LSTM	98K	20.02	32.41	11.36%	27.73	44.05	16.49%	39.55	61.65	25.68%	28.05	44.38	17.23%
DCRNN	373K	18.41	29.23	10.94%	23.16	36.15	14.14%	30.26	46.85	19.68%	23.17	36.19	14.40%
AGCRN	792K	17.27	29.70	10.78%	20.38	34.82	12.70%	24.59	42.59	16.03%	20.25	34.84	12.87%
STGCN	2.1M	19.86	34.10	12.40%	22.75	38.91	14.11%	26.70	45.78	17.00%	22.64	38.81	14.17%
GWNET	374K	17.28	27.68	10.18%	21.31	33.70	13.02%	26.99	42.51	17.64%	21.20	33.58	13.18%
ASTGCN	59.1M	21.89	34.17	13.29%	29.54	45.01	19.36%	39.02	58.81	29.23%	28.99	44.33	19.62%
STGODE	841K	18.10	30.02	11.18%	21.71	36.46	13.64%	26.45	45.09	17.60%	21.49	36.14	13.72%
DSTAGNN	66.3M	19.49	31.08	11.50%	24.27	38.43	15.24%	30.92	48.52	20.45%	24.13	38.15	15.07%
CA	HL	-	30.72	46.96	20.43%	51.56	76.48	37.22%	89.31	125.71	76.80%	54.10	78.97	41.61%
LSTM	98K	19.04	31.28	13.19%	26.49	42.63	19.57%	38.22	60.29	30.28%	26.89	43.11	20.16%
DCRNN	373K	17.55	28.21	12.68%	21.79	34.27	16.67%	28.56	44.34	23.84%	21.87	34.41	17.06%
STGCN	4.5M	18.99	32.37	14.84%	21.37	36.46	16.27%	24.94	42.59	19.74%	21.33	36.39	16.53%
GWNET	469K	17.14	27.81	12.62%	21.68	34.16	17.14%	28.58	44.13	24.24%	21.72	34.20	17.40%
STGODE	1.0M	17.57	29.91	13.91%	20.98	36.62	16.88%	25.46	45.99	21.00%	20.77	36.60	16.80%